Calculus 2 QuickStudy .pdf
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Calculus 2.qxd
12/6/07
1:46 PM
Page 1
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Series continued
3
/ a n =S means the series converges
and its sum is S. In general statements, / a n may stand for
3
/ a n =S.
An equation such as
n=0
n=0
• Geometric series. A (numerical) geometric series has the
3
form
/ ar n, where r is a real number and a≠ 0. A key identity
n=0
N
n
N+1
] r!1 g . It implies
is / r =1+r +r2 +...+r N=1r
1r
n =0
1 ^ if r <1 h e also / ar n =a b 1 1 lo,
/ r n = 1r
1r
3
3
n=0
n=1
and
that the series diverges if r>1. The series diverges if
r=± 1. The convergence and possible sum of any geometric
series can be determined using the preceding formula.
The pseries and geometric series are often used for
comparisons. Try a “limit” comparison when a series
looks like a pseries, but is not directly comparable to it.
3
sin ^ 1/n 2 h
E.g., / sin ^ 1/n 2 h converges since lim
=1.
n"3
1/n 2
n=K
• Ratio & root tests. Assume an ≠ 0.
a n+1
If lim a <1 or lim a n 1/n <1, then / a n converges
n"3
n"3
n
a n+1
1/n
(absolutely). If lim a >1 or lim a n >1, then
n"3
n"3
n
/ a n diverges. These tests are derived by comparison with
geometric series. The following are useful in applying the
root test: lim n p/n =1 (any p) and lim ] n! g 1/n =3. More
3
/ n1P is called the pseries.
n=1
The pseries diverges if p≤1 and converges if p>1 (by
comparison with harmonic series and the integral test,
3
1 diverges, for the partial
below). The harmonic series / n
n=1
2N
1 $1+ N .
sums are unbounded: / n
2
n=1
• Alternating series. These are series whose terms alternate
in (nonzero) sign. If the terms of an alternating series
strictly decrease in absolute value and approach a limit of
zero, then the series converges. Moreover, the truncation
error is less than the absolute value of the first omitted
/ ] 1 g
3
term:
n
a n  / ] 1 g a n <a N+1 . (assuming
N
n
an → 0 in a strictly decreasing manner).
n=1
n=1
CONVERGENCE TESTS
3
/ a n converges, then
n=K
If a n " 0, then / a n
• Basic considerations. For any K, if
3
/ an
converges, and conversely.
n=1
diverges. (Equivalently, if / a n converges, then an→0). This
3
says nothing about, e.g.,
/ n1 . A series of positive terms is
n=K
an increasing sequence of partial sums; if the sequence of
partial sums is bounded, the series converges. This is the
foundation of all the following criteria for convergence.
• Integral test & estimate. Assume f is continuous,
∞). Then
positive, and decreasing on (K,∞
#K 3f ] xg dx,
if and only if
3
/
converges, then
n=K
f ] n g#
/ f ]ng converges
3
n=K
converges. If the series
N
/
n=K
f ] n g + # f ] x g dx, the
POWER SERIES
• Power series. A power series in x is a sequence of
N
n= 0
3
N
/ 13 . / n13 + #133 x13 dx=1.2018..., the left side
n =1 n
n =1
underestimating the sum with error less than f (N+1).
Integral test
n=0
/ a n ] xcgn =a 0 +a 1 ] xcg +a 2 ] xcg2 +f.
3
n=0
Replacing x with a real number q in a power series yields
a series of real numbers. A power series converges at q if
the resulting series of real numbers converges.
• Interval of convergence. The set of real numbers at which
a power series converges is an interval, called the interval
of convergence, or a point. If the power series is centered
at c, this set is either (i) (– ∞, ∞); (ii) (c – R, c + R) for some
R>0, possibly together with one or both endpoints; or (iii)
the point c alone. In case (ii), R is called the radius of
convergence of the power series, which may be ∞ and 0
for cases (i) and (iii), respectively. Convergence is absolute
for  x– c < R. You can often determine a radius of
convergence by solving the inequality that puts the ratio
(or root) test limit less than 1. E.g., for
3
n +1
n 2
x
x
: 2 nn / <1& x <2,
/ xn 2, nlim
"3 2 n+1 ] n+1 g 2
2
x
n =1 2 n
which, with the ratio test, shows that the radius of
convergence is 2.
• Geometric power series. A power series determines a
function on its interval of convergence:
n
x " f ] x g= / a n ] xc g n . One says the series converges
3
n= 0
3
N
x N+1 ] x!1 g,
/ x n =1+x+x2+…+xN= 11x
n=0
polynomials
converges for x in the interval (–1,1) to 1/(1–x) and
n=0
geometric series may be identified through this basic one.
/ 2:3 n x n =2 x3 / b x3 l
3
E.g.,
3
E.g.,
/ 13
n=1 n
≈
12
/ 13
n=1 n
+
#13
3
1 dx
x3
= 1.2018..., an
underestimate with error <13–3 <5•10– 4.
• Absolute convergence. If / a n converges, that is, if
/ a n {converges absolutely}, then / a n converges, and
3
3
n=1
n =1
/ an # / an . A
n=0
n
= 2x : 1 ,
3 1x/3
for
x/ 3< 1. The interval of convergence is (–3,3).
• Calculus of power series. Consider a function given by a
power series centered at c with radius of convergence R:
N+1
N
/ x n = 11 x ^ x <1h . Other
3
n =0
3
, i.e., the sequence of
n=0
N
3
f (N+1)
/x
to the function. The series
n
series converges conditionally if it
converges, but not absolutely.
• Comparison tests. Assume an , bn >0.
 If / b n converges and either an £bn (n≥ N ) or an / bn
has a limit, then / a n converges.
3
n
ln ] 1+x g= / ] 1 g n+1 xn for x < 1; a remainder
n=1
argument (see below) implies equality for x =1.
• Taylor and MacLaurin series. The Taylor series
about c of an infinitely differentiable function f is
]kg
3
/ f k!]cg ] xcgk= f (c) + f'(c)(x – c) + f l2l!]cg ] xcg2+g.
k=0
If c = 0, it is also called a MacLaurin series. The Taylor
series at x may converge without converging to f (x). It
converges to f (x) if the remainder in Taylor’s formula,
]
g
R n ] x g= 1
f ]n+1g _ p i:] xc g n+1 (ξξ between c and x,
] n+1 g !
ξ varying with x and n), approaches 0 as n → ∞. E.g., the
remainders at x =1 for the MacLaurin polynomials of
ln(1 + x) (in Taylor’s formula above) satisfy
1
# 1 "0,
R n ]1g =
] n+1 g _ 1+p i n+1 n+1
] 1 g n+1
n .
n=1
3
so ln 2= /
• Computing
A power series in x–c (or “centered at c” or “about c”) is written
diverges otherwise. That is,
!n = K f ^nh . !n = K f ^nh + #N + 1 f ^ xh dx
K
/ an xn .
The power series is denoted
3
12
3
/ a n x n ^ N=0, 1, 2, fh .
polynomials in x of the form
right side overestimating the sum with error less than
3
n"3
n"3
1 ] n! g 1/n = 1 .
precisely, nlim
e
"3 n
E.g., / 4n =4 c 1 1 1 m=2.
1 3
n= 1 3
3
• pseries. For p, a real number,
 If / b n diverges and either bn £an (n≥ N ) or an / bn has
a nonzero limit (or approaches ∞), then / a n diverges.
f(x)=
Taylor
series.
/ a n ] xcgn ^ xc <R h,
1 = / nx n1= / ] n+1 g x n ^ x <1 h .
series gives
] 1x g 2 n=1
n=0
• Basic MacLaurin series:
3
3
1 =1+x+x2 + ...= / x n ^ x <1 h
1x
n=0
3
3
n
x 2 + x 3 – ... = /
] 1 g]n+1 g x ] 11x#1 g
n
2 3
n=1
ln 1+x =2 c x+ x
3
1x
3
3
arctan x=x – x
3
+
5
+
x 5 +g m=2 / x 2n+1 ^ x <1 h
5
n=0 2n+1
3
x
5
The differentiated series has radius of convergence R, but
may diverge at an endpoint where the original converged.
Such a function is integrable on (c – R, c + R), and its
integral vanishing at c is:
#c
a
f ] t g dt= / n ] xc g n+1 ^ xc <R h .
n=0 n+1
x
3
4
INTEGRATION
DEFINITIONS
INTERPRETATIONS
• Heuristics. The definite integral captures the idea of
adding the values of a function over a continuum.
• Riemann sum. A suitably weighted sum of values. A
definite integral is the limiting value of such sums. A
Riemann sum of a function f defined on [a, b] is
determined by a partition, which is a finite division of
[a, b] into subintervals, typically expressed by
a = x0< x1···< xn= b; and a sampling of points, one point
from each subinterval, say ci from [xi –1, xi ]. The associated
• Area under a curve. If f is nonnegative and continuous on
Riemann sum is:
g=
A regular partition has subintervals all the same length,
∆ x = (b – a) / n, xi = a + i ∆ x. A partition’s norm is its
maximum subinterval length. A left sum takes the left
endpoint ci = xi –1 of each subinterval; a right sum, the
right endpoint. An upper sum of a continuous f takes a
point ci in each subinterval where the maximum value of f
is achieved; a lower sum, the minimum value. E.g., the
upper Riemann sum of cosx on [0,3] with a regular
partition of n intervals is the left sum (since the cosine is
3 l +1D 3 .
decreasing on the interval): / :cos b]i1g n
n
i=1
n
Riemann sum
2n+1
n=0
1
2
3
• Definite integral. The definite integral of f from a to b
3
2
4
] 1 g n x 2n
cos x=1x+ x + x g= /
] 2n g !
2! 4!
n =0
may be described as
[a, b], then
the area accumulated up to x. If f is negative, the integral
is the negative of the area.
• Average value. The average value of f over an interval [a,b]
b
may be defined by average value = 1 # f ]xgdx.
ba a
A rough estimate of an integral may be made by estimating
the average value (by inspecting the graph) and
multiplying it by the length of the interval. (See Mean
Value Theorem (MVT) for integrals, in the Theory section.)
• Accumulated change. The integral of a rate of change of
a quantity over a time interval gives the total change in the
quantity over the time interval. E.g., if v(t)= s'(t) is a
velocity (the rate of change of position), then v(t)∆t is the
approximate displacement occurring in the time increment
t to t+∆t; adding the displacements for all time increments
gives the approximate change in position over the entire
time interval. In the limit of small time increments, one
gets the exact total displacement:
#a
v ]t gdt=s(b)– s(a).
b
• Integral curve. Imagine that a function f determines a
slope f (x) for each x. Placing line segments with slope
f (x) at points (x, y) for various y, and doing this for various
x, one gets a slope field. An antiderivative of f is a function
whose graph is tangent to the slope field at each point. The
graph of the antiderivative is called an integral curve of
the slope field.
• Solution to initial value problem. The solution to the
differential equation y' = f (x) with initial value y(x0 )=y0 is
Fundamental Theorem
f(x)
f(x)
A(x)
h
a
x
• Differentiation of integrals. Functions are often defined
as integrals. E.g., the “sine integral function” is
x
Si ]xg= # b sin t ldt.
t
0
To differentiate such, use the second part of the
fundamental theorem: Si'(x) = sin x /x. A function
#a f ]t gdt
x2
such as
is a composition involving
A ]ug= # f ]t gdt. To differentiate, use the chain rule
u
a
and the fundamental theorem:
x
d
d A ^x 2h=A’ ^x 2h2x=2xf ^x 2h.
# f ]t gdt= dx
dx a
• Mean value theorem for integrals. If f and g are
continuous on [a,b], then there is a ξ in [a,b] such that
2
#a f ]xgg ]xgdx=f _pi #a g ]xgdx.
b
b
In the case g ≡ 1, the average value of f is attained
b
somewhere on the interval: 1 # f ]xgdx=f _pi.
ba a
]xg=y 0 + # f ]t gdt.
value is denoted
The binomial coefficients are e o=1, e o=p, e o=
p ^ p 1 h
, and (“p choose k ”)
2
p
p ^ p1 h ^ p2 h g ^ pk+1 h
e o=
k!
k
b
p
p
p
0
1
2
#a f ] xg dx or #a f . The function must be
b
b
bounded to be integrable. The function f is called the
integrand and the points a and b are called the lower limit
and upper limit of integration, respectively. The word
integral refers to the formation of
If p is a positive integer, e o= 0 for k > p.
p
k
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QuickStudy as a guide, but
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THEORY
i
2n+1
MVT for Integrals
x0
/ f ]c ig Ds i .
#a f ] xg dx= Dlim
x "0
The limit is said to exist if some number S (to be called the
integral) satisfies the following: Every ε > 0 admits a δ
such that all Riemann sums on partitions of [a, b] with
norm less than δ differ from S by less than ε . If there is
such a value S, the function is said to be integrable and the
] 1 g x
sin x=x x + x g= /
] 2n+1 g !
3 ! 5!
n =0
• Binomial series. For p≠ 0, and for x<1,
3 p
p ^ p 1 h 2
] 1+x g p =1+px+
x +g= / e o x k .
2!
n= 0 k
n
3
quickstudy.com
cos ; i  1 E + 1 1
2
2
#b af ]xgdx gives the area between the xaxis
x
and the graph. The area function A ]xg= # f ]t gdt gives
a
A' (x) = f (x) (valid for onesided derivatives at the
endpoints).
x
3
2
n
3
e =1+x+ x + x +g= / x
2! 3!
n=0 n!
free downloads &
hundreds of titles at
!
i =1
1
x
5
6
2
The following hold for all real x:
3
/ f ]c ig ] x i x i1g .
n
^ x #1 h
/ ]1gn 2xn+1
3
n=0
3
then the coefficients are
necessarily the Taylor coefficients: an = f (n)(c) / n!. This
means Taylor series may be found other than by directly
computing coefficients. Differentiating the geometric
Such a function is differentiable on (c– R, c+R), and its
n=1
and
3
n
derivative there is f l ] x g= / na n ] xc g n1 .
R>0
If
n=0
ln(1+x)=x–
INTEGRAL & DIFFERENTIAL CALCULUS FOR ADVANCED STUDENTS
i=1
f ] x g= / a n ] xc g .
3
WORLD’S #1 ACADEMIC OUTLINE
The integrated series has radius of convergence R, and may
converge at an endpoint where the original diverged.
E.g., 1 =1x+x 2 g implies 1 =1x+x 2 g.
1+x
1+x
The initial (geometric) series converges on (–1, 1), and the
integrated series converges on (1, –1). The integration says
• Integrability & inequalities. A continuous function on a
closed interval is integrable. Integrability on [a, b] implies
integrability on closed subintervals of [a, b]. Assuming f is
integrable, if L≤ f (x)≤ M for all x in [a, b], then
L:] ba g# # f ] x g dx#M:] ba g .
b
a
Use this to check integral evaluations with rough
overestimates or underestimates.
b
#a f from f and [a,b], as
well as to the resulting value if there is one.
• Antiderivative. An antiderivative of a function f is a
function A whose derivative is f: A' (x)= f (x) for all x in
some domain (usually an interval). Any two antiderivatives
of a function on an interval differ by a constant (a
consequence of the Mean Value Theorem). E.g., both
1 ] xa g 2 and 1 x 2 ax are antiderivatives of x – a ,
2
2
differing by 1 a 2. The indefinite integral of a function f,
2
denoted #f ] x g dx, is an expression for the family of
antiderivatives on a typical (often unspecified)
interval. E.g., (for x < –1, or for x >1).
# 2x dx= x 2 1 +C.
x 1
The constant C, which may have any real value, is the
constant of integration. (Computer programs, and this
chart, may omit the constant, it being understood by the
knowledgeable user that the given antiderivative is just one
representative of a family.)
Basic Integral Bounds
M
a
b
• Change of variable formula. An integrand and limits of
integration can be changed to make an integral easier to
apprehend or evaluate. In effect, the “area” is smoothly
redistributed without changing the integral’s value. If g is
a function with continuous derivative and f is continuous,
then
#a
b
f ] u g du= # f ^ g ] t gh gl ] t g dt, where c, d are
d
c
points with g(c)= a and g(d )=b.
In practice, substitute u=g (t); compute du=g'(t)dt; and
find what t is when u=a and u=b. E.g., u=sin t effects the
L
a
b
If f is nonnegative, then
#a f ]xgdx is nonnegative.
b
If f is integrable on [a, b], then so is f, and
#a
f ] x g dx # #
b
a
b
f ] x g dx.
f ] x g dx=A ] x g a/ A ] b g A ] a g .
b
b
which becomes
The other part is used to construct antiderivatives:
If f is continuous on [a, b], then the function
A ]xg = # f ]t gdt is an antiderivative of f on [a, b]:
x
a
1
#a
b
#0
1u 2 du= #
r/2
0
r/2
cos 2 t dt, since
1sin 2 t cos t dt,
1sin 2 t =cos t
for 0#t#r/2. The formula is often used in reverse,
starting with
• Fundamental theorem of calculus. One part of the
theorem is used to evaluate integrals: If f is continuous on
[a, b], and A is an antiderivative of f on that interval, then
#a
transformation
#b aF ^ g ] xgh gl ] xg dx. See Techniques on pg. 2.
• Natural logarithm. A rigorous definition is ln x =
#1 x u1 du. The change of variable formula with u=1/t
x1
x 1
1
u du = #1 t t 2 dt =  #1 t dt showing that
ln(1/x) = – ln x. The other elementary properties of the
natural log can likewise be easily derived from this
definition. In this approach, an inverse function is deduced
and is defined to be the natural exponential function.
yields
#1
1/x
Calculus 2.qxd
12/6/07
1:46 PM
Page 3
INTEGRATION FORMULAS
• Basic indefinite integrals. Each formula gives just one
antiderivative (all others differing by a constant from that
given), and is valid on any open interval where the
integrand is defined:
n+1
# x n dx= nx+1 ]n! 1g
# x1 dx=ln x
n
kx
#e kx dx= ek ]k!0g
#a x dx= lna a ]a!1g
#cos x dx=sin x
dx =arctan x
#1+
x2
#sin x dx= cos x
# dx 2 =arcsin x
1x
• Further indefinite integrals. The above conventions hold:
#cot x dx=ln sin x
#tan x dx=ln sec x
#sec x dx=ln sec x+tan x
#csc x dx=ln csc x+cot x
#cosh x dx=sinh x
#sinh x dx=cosh x
= 1 ln xa
# x 2dx
# x dx= 12 x x
a 2 2a x+a
dx =ln x+ x 2 +a 2 =sinh 1 x +ln a
a
x 2 +a 2
# dx2 2 =ln x+ x 2 a 2 cosh 1 ax +ln a
x a
(take positive values for cosh1)
2
# x 2 !a 2 dx= 12 x x 2 a 2 ! a2 ln x+ x 2 !a 2
(Take same sign, + or –, throughout)
2
# a 2 x 2 dx= 12 x a 2 x 2 + a2 arcsin ax
• Common definite integrals:
2
1
¹
1
#0 x n dx= n+
# r r 2x 2 dx= ¹4r #0 sin x dx=2
1 0
¹/2
¹/ 2
2θ dθ= ¹
#0 cos 2 θdθ= #0 1+cos
4
2
¹/2
¹/2
2θ dθ= ¹
#0 sin 2 θdθ= #0 1cos
4
2
θ ) equals cos2θ or
To remember which of 1/2 (1± cos 2θ
sin2θ, recall the value at zero.
#
Other routine integrationbyparts integrands are arcsin x,
ln x, x n ln x, x sin x, x cos x, and xe ax.
• Rational functions. Every rational function may be
written as a polynomial plus a proper rational function
(degree of numerator less than degree of denominator). A
proper rational function with real coefficients has a partial
fraction decomposition: It can be written as a sum with
each summand being either a constant over a power of a
linear polynomial or a linear polynomial over a power of a
quadratic. A factor (x– c) k in the denominator of the
rational function implies there could be summands
Ak
A1
xc +f+ ] xc g k .
A factor (x2 +bx +c)k (the quadratic not having real roots)
in the denominator implies there could be summands
A k +B k x
A 1 +B 1 x
+f+
.
x 2 +bx+c
] x 2 +bx+c g k
Math software can handle the work, but the following case
1
= C + D
should be familiar. If a ≠ b,
] xa g ] xb g xa xb
where C, D are seen to be C= D= 1 .
ab
1
dx= 1 ^ ln xa ln xb h .
Thus #
] xa g ] xb g
ab
In general, the indefinite integral of a proper rational function
can be broken down via partial fraction decomposition and
linear substitutions (of form u = ax+b) into the integrals
#u 1 du, #u n du ]n21g, #u ]u 2 +1gn du (handled with
n
substitution w = u2 +1), and #] u 2 +1 g du (handled with
substitution u = tan t ).
• Substitution. Refers to the Change of variable formula
(see the Theory section), but often the formula is used in
reverse. For an integral recognized to have the form
#a F ^ g ] xgh gl ] xg dx (with F and g' continuous), you can put
b
u=g (x), du=g'(x)dx, and modify the limits of integration
appropriately:
g ]bg
#a F ^ g ] xgh gl ] xg dx= #g ]ag F ]ug du.
b
In effect, the integral is over a path on the uaxis traced out
by the function g. (If g(b) = g(a) [the path returns to its
start], then the integral is zero.) E.g., u=1+x 2 yields
1
1
#0 = 1+xx 2 dx= 12 #0 1+1x 2 2 x dx= 12 ln ]1+x 2g .
Substitution may be used for indefinite integrals.
= 1 ln u= 1 ln ] 1+x 2 g .
E.g., # x 2 dx= 1 # du
2 u
2
2
1+x
Some general formulas are:
n+1
# g ] xgn gl ] xg dx= gn] x+g 1 , # ggl]]xxgg dx=ln g ] xg ,
IMPROPER INTEGRALS
b
b
b
b
#a u dv=uv ba  #a v du.
For indefinite integration, #u dv=uv #v du.
The common formula is
The procedure is used in derivations where the functions
are general, as well as in explicit integrations. You don’t
need to use “u” and “v.” View the integrand as a product
with one factor to be integrated and the other to be
differentiated; the integral is the integrated factor times the
one to be differentiated, minus the integral of the product
of the two new quantities. The factor to be integrated may
be 1 (giving v = x).
E.g., #arctan x dx=x arctan x # x 2 dx
1+x
APPLICATIONS
∞] and integrable
• Unbounded limits. If f is defined on [a,∞
on [a,B] for all B> a, then
#a
f ] x g dx = lim
provided the limit exists.
E.g.,
#0
3 x
e
dx= lim ] 1e
def
3
B
B"3
#
f ] x g dx
B
B"3 a
• Areas of plane regions. Consider a plane region admitting
an axis such that sections perpendicular to the axis vary in
length according to a known function L(p), a≤ p≤ b. The
area of a strip of width ∆p perpendicular to the axis at p is
∆A=L( p)∆p, and the total area is A= # L ^ p h dp. E.g.,
b
#33 f ] xg dx = Alim
# cf ] xg dx+Blim
#
"3 c
"3 A
def
f ] x g dx = lim
def
#
c"a + c
f ] x g dx
B
(the
f ] x g dx provided the limit exists. A
b
similar definition holds if the integrand is defined on
2
c
1
1
[a, b). E.g., #
dx=
dx is lim #
c"2 0
0
4x 2
4x 2
lim arcsin b c l= r .
2
2
c"2


Singular Integrand
1
#0
c
1
dx = arcsin c c m "
4  x2
1
a
c
6 g ] x g f ] x g@ dx , provided g(x)≥ f (x) on
[a,b]. Sometimes it is simpler to view a region as bounded
by two graphs “over” the yaxis, in which case the
integration variable is y.
2
If f is not defined at a finite number of points in an interval
[a,b], and is integrable on closed subintervals of open
#a
b
f is defined
as a sum of left and righthand limits of integrals over
appropriate closed subintervals, provided all the limits exist.
1
1
a
E.g., # 13 dx= lim # 13 dx+ lim # 13 dx if the
a"0 1 x
b"0 b x
1 x
limits on the right were to exist. They don’t, so the integral
diverges.
• Examples & bounds.
#1 3x1p dx converges for p >1, diverges otherwise.

+
2
y(t)), a≤t≤b, has length
#C ds= #a
b
xl ] t g 2 +yld ] t g 2 dt .
• Area of a surface of revolution. The surface generated by
revolving a graph y =f(x) between x = a and x = b about the
xaxis has area
#b a 2¹ f ] xg
1+f l ] x g 2 dx . If the
generating curve C is parametrized by ((x(t), y(t)),
a≤t≤b, and is revolved about the x axis, the area is
#C 2¹ yds= #a 2¹ y ] t g
b
xl ] t g 2 +yl ] t g 2 dt .
PHYSICS
• Motion in one dimension. Suppose a variable
displacement x(t) along a line has velocity v(t)=x'(t) and
acceleration a(t)=v'(t). Since v is an antiderivative of a,
the fundamental theorem implies: v(t) = v (t0) +
#t
t
a ] u g du, x ] t g=x ] t 0 g + # v ] u g du. E.g., the height x(t)
t
t0
– g due to gravity. Thus v(t) = v(v0) +
and x(t) = x0 +
#0
t
] u g du = v0 – gt
#0 ^v 0 guh du = x0 + v0t–12 gt 2 .
• Work. If F(x) is a variable force acting along a line
parametrized by x, the approximate work done over a small
displacement ∆x at x is ∆W = F(x)∆x (force times
displacement), and the work done over an interval [a,b] is
W= # F ] x g dx.
b
In a fluid lifting problem, often ∆W = ∆F•h( y), where
h( y) is the lifting height for the “slab” of fluid at y with
crosssectional area A( y) and width ∆y, and the slab’s
weight is ∆F= ρ A( y)∆y, ρ being the fluid’s weightdensity.
a
Then W= # tA ^ y h h ^ y h dy.
b
a
DIFFERENTIAL EQUATIONS
a
b
p
• Volumes of solids.
Consider
a
solid
admitting an axis such
that
crosssections
perpendicular to the
axis vary in area
according to a known
function A( p), a≤ p≤b.
The volume of a slab of
thickness ∆p perpendicular to the axis at p is ∆V = A( p)∆p,
and the total volume is V= # A ^ p h dp. E.g., a pyramid
b
a
having square horizontal crosssections, with bottom side
length s and height h, has crosssectional area
A(z) = [s (1– z / h)]2 at height z. Its volume is thus
2
2
h
V= # s 2 c 1 z m dz= s h .
3
h
0
• Solids of revolution. Consider a solid of revolution
determined by a known radius function r(z), a≤ z≤ b, along
its axis of revolution. The area of the crosssectional
“disk” at z is A(z) = π r(z)2, and the volume is
V= # A ] z g dz= #
b
a
intervals between such points, the integral
a
1+f l ] x g 2 dx . A curve C parametrized by ((x(t),
b
choice of c being arbitrary), provided each integral on the
right converges.
• Singular integrands. If f is defined on (a,b] but not at
x = a and is integrable on closed subintervals of (a,b], then
b
b
#3 f ] xg dx = Alim
# f ] xg dx.
"3 A
In each case, if the limit exists, the improper integral
converges, and otherwise it diverges. For f defined on
(– ∞, ∞) and integrable on every bounded interval,
#a
#a
Planar Area
def
V= #
b
of an object thrown at time t 0 =0 from a height x(0) = x0
with a vertical velocity v(0)=v0 undergoes the acceleration
GEOMETRY
g=1
b
• Arc length. A graph y =f (x) between x= a and x=b has length
0
over [a,b] is
g ] xg
#a u ] xg vl ] xg dx=u ] xg v ] xg ba  #a v ] xg ul ] xg dx.
3/2
E.g., # c x 2 m dx converges since the integrand is
0
1+x
bounded by 1/2 3/2} on [0,1] and is always less than 1/x 3/2.
It
converges
to
a
number
less
than
1 # 3 1 dx= 1 +212.4.
2 3/2 1 x 3/2
2 3/2
3
the area of the region bounded by the graphs of f and g
#e gl ] xg dx=e .
• Integration by parts. Explicitly,
g ] xg
1
a
Likewise, for appropriate f,
TECHNIQUES
1 dx converges for p <1, diverges otherwise.
xp
#2 3 x ]ln1 xg p dx converges for p > 1, diverges otherwise.
1
Note: # dx p = , p >1 converges at
x ] ln x g
] n1 g ] ln x g p1
x= ∞, p = 0 or < 1 diverges at x= ∞.
1
3
E.g., # 12 dx converges to 1 and # 12 dx diverges.
1 x
0 x
The above integrals are useful in comparisons to
establish convergence (or divergence) and to get bounds.
#0
a
¹r ] z g dz.
b
2
If the solid lies between two radii r1(z) and r2(z) at each
point z along the axis of revolution, the crosssections
are “washers,” and the volume is the obvious
difference of volumes like that above. Sometimes
a radial coordinate r, a≤ r≤ b, along an axis
perpendicular to the axis of revolution,
parametrizes the heights h (r) of cylindrical
sections (shells) of the solid parallel to the axis of
revolution. In this case, the area of the shell at r is
A(r) = 2 π r h(r), and the volume of the solid is
V= # A ] r g dr= # 2¹rh ] r g dr.
b
a
b
a
• Examples. A differential equation (DE) was solved in the
item Solution to initial value problem; an example of that
type is in Motion in one dimension. In those, the expression
for the derivative involved only the independent variable. A
basic DE involving the dependent variable is y' =ky. A
general DE where only the first–order derivative appears
and is linear in the dependent variable is y'+ p(t) y = q(t).
Generally more difficult are equations in which the
independent variable appears in a \hlt{nonlinear} way;
e.g., y'= y 2 – x. Common in applications are secondorder
DEs that are linear in the dependent variable; e.g.,
y'' = – k y, x 2 y'' + xy'+ x 2 y = 0.
• Solutions. A solution of a DE on an interval is a function
that is differentiable to the order of the DE and satisfies the
equation on the interval. It is a general solution if it
describes virtually all solutions, if not all. A general
solution to an nth order DE generally involves n constants,
each admitting a range of real values. An initial value
problem (IVP) for an nth order DE includes a specification
of the solution’s value and n–1 derivatives at some point.
Generally in applications, an IVP has a unique solution on
some interval containing the initial value point.
• Basic firstorder linear DE. The equation y' = ky,
dy
dy
rewritten
=ky suggests y =kdt where y =kt + c. In
dt
this way, one finds a solution y = Ce kt. On any open
interval, every solution must have that form, because
y'= ky implies d ^ ye kt h, where ye – k t is constant on the
dt
interval. Thus y = Ce k t (C real) is the general solution. The
unique solution with y(a)= ya is y = ya e k(t– a). The trivial
solution is y≡0, solving any IVP y(a)=0.
• General firstorder linear DE. Consider
y' + p(t) y = q(t ). The solution to the associated
homogeneous equation h'+p(t)h=0(dh/h = –p(t)dt)
with h(a)=1 is h ] t g=exp ;  # p ] u g du E .
t
a
If y is a solution to the original DE, then (y/h)' =q/h,
where y=h #q/h. The solution with y (a) = ya is
y(t)=Ya+;  # q ] u g h ] u g 1 du E .
t
a
APPROXIMATIONS
TAYLOR’S FORMULA
• Taylor polynomials. The nth degree Taylor polynomial of
f at c is Pn(x) = f (c) + f '(c) (x – c) + 1 ! f''(c) (x – c) 2 +...+
2
1 f (n)(c)(x–c) n (provided the derivatives exist). When
n!
c= 0, it’s also called a MacLaurin polynomial.
• Taylor’s formula. Assume f has n+1 continuous
derivatives on open interval and that c is a point in the
interval. Then for any x in the interval, f (x)= Pn (x)+Rn(x),
1
f ]n+1g _ p i • (x–c)n+1 for some ξ
where Rn(x) =
] n+1 g !
between c and x (ξ varying with x). The expression for
Rn(x) is called the Lagrange form of the remainder. E.g.,
the remainders for the MacLaurin polynomials of f (x) =
] 1 g n
l n(1+x), –1< x<1, are Rn(x) =
• x n+1.
] n+1 g _ 1+p i n+1
There is a ξ between 0 and x such that ln(1 + x) =
2
1
.
x x +
2 3 _ 1+p i 3
• Error bounds. As x approaches c, the remainder generally
becomes smaller, and a given Taylor polynomial provides a
better approximation of the function value. With the
assumptions and notation above, if f ]n+1g ] x g is bounded
f ] x g Pn ] x g
by M on the interval, then
n+1
M
≤
for all x in the interval. E.g., for x<1,
xc
] n+1 g !
e x≈1+x+x2/ 2, with error no more than 3 x 3 =0.5 x 3,
3!
because the third derivative of e x is bounded by 3 on (–1,1).
• Big O notation. The statement f (x)=p(x)+ O(xm)
f ] x g p ] x g
→0) means that
(as x→
is bounded near x = 0.
xm
(Some authors require that the limit of this ratio as x
approaches 0 exist.) That is, f (x)–p(x) approaches 0 at
essentially the same rate as x m. E.g., Taylor’s formula
implies f (x)=f (0)≠f ' (0)x + 1 f ''(0)x2 +O (x3) if f has
2
continuous third derivative on an open interval containing
0. E.g., sinx =x + O(x3). [Similar relations can be inferred
from the identities in the item Basic MacLaurin Series.]
• L’Hôpital’s rule. This resolves indeterminate ratios or
b 0 or 3
l . If lim f ] x g = 0 = lim g ] x g and if limlf ] x g = 0
x "a
x "a
x "a
0 3
= limlg ] x g are defined and g(x)≠0, for x near a (but not
x "a
f ] xg
f l ] xg
=0=lim
provided
x"a gl ] x g
g ] xg
the latter limit exists, or is infinite. The rule also holds
when the limits of f and g are infinite. Note that f'(a) and
g'(a) are not required to exist. To resolve an indeterminate
∞ – ∞), try to rewrite it as an indeterminate
difference (∞
ratio and apply L’Hôpital’s rule. To resolve an
indeterminate exponential (00, 1∞,or ∞0), take its logarithm
to get a product and rewrite this as a suitable indeterminate
ratio; apply L’Hôpital’s rule; the exponential of the result
resolves the original indeterminate exponential.
1/x
ln x
For lim x x you get and find limx→
=limx→
=0,
→0
→0
x"0
1/x 2
1/x
x
0
where lim x = e = 1.
necessarily at a), then lim
x "a
x"0
NUMERICAL INTEGRATION
• General notes. Solutions to applied problems often
involve definite integrals that cannot be evaluated easily, if
at all, by finding antiderivatives. Readily available
software using refined algorithms can evaluate many
integrals to needed precision. The following methods for
approximating
#b af ] xg dx are elementary. Throughout, n is
the number of intervals in the underlying regular partition
and h =(b – a)/n.
• Trapezoid rule. The line connecting two points on the
graph of a positive function together with the underlying
interval on the x axis form a trapezoid whose area is the
average of the two function values times the length of the
interval. Adding these areas up over a regular partition
gives the trapezoid rule approximation
3
f ] a g n 1
f ]bg
o h. This is also the
+ / f ] aih g +
2
2
i=1
average of the left sum and right sum for the given partition.
The approximation remains valid if f is not positive.
• Midpoint rule. This evaluates the Riemann sum on a
regular partition with the sampling given by the midpoints
Tn =e
of each interval: M n = / f c a+: i 1 D h m h. Each
2
I=0
summand is the area of a trapezoid whose top is the
tangent line segment through the midpoint.
• Simpson’s rule. The weighted sum 1 T1 + 2 M 1 on the
3
3
interval
[a, b]
yields
Simpson’s
rule
b
a
a
+
b
c f ] a g+4 f b
l+f ] b gm .
S=
6
2
This is also the integral of the Simpson's Rule
quadratic that interpolates the
function at the three points. For
a regular partition of [a, b] into
an even number n = 2m of
a
a+b
b
intervals, a formula is:
2
n1
S 2m=h " f ] a g+ 4 / f ] a g+[2i+1]h+ 2 / f (a+2i•h)+ f ] b g,
3
i=0
i=0
where h = (b – a)/n. Simpson’s rule is exact on cubics.
m1
m1
SEQUENCES & SERIES
SEQUENCES
• Sequences. Sequences are functions whose domains
consist of all integers greater than or equal to some initial
integer, usually 0 or 1. The integer in a sequence at n is
usually denoted with a subscripted symbol like an (rather
than with a functional notation a(n)) and is called a term
of the sequence. A sequence is often referred to with an
expression for its terms, e.g., 1/n (with the domain
understood), in lieu of a fuller notation like:
" 1/n , 3 , or n;" 1/n ^ n=1, 2, f h .
n=1
• Elementary sequences. An arithmetic sequence an has a
common difference d between successive values:
an =an–1 +d=a0 +d·n. It is a sequential version of a linear
function, the common difference in the role of slope. A
geometric sequence, with terms gn, has a common ratio r
between successive values: gn = gn1 r=g0 r n. E.g., 5.0, 2.5,
1.25, 0.625, 0.3125,.... It is a sequential version of an
exponential function, the common ratio in the role of base.
• Convergence. A sequence {an} converges if some number
L (called the limit) satisfies the following: Every ε > 0
admits an N such that an – L< ε for all n≥ N. If a limit L
exists, there is only one; one says {an}converges to L, and
writes an→L, or lim a n =L. If a sequence does not
n"3
converge, it diverges. If a sequence an diverges in such a
way that every M> 0 admits an N such that an >M for all
n≥ N, then one writes an → ∞. E.g., if r<1 then r n→ 0; if
r = 1 then r n → 1; otherwise rn diverges, and if r>1, r n →∞.
• Bounded monotone sequences. An increasing sequence
that is bounded above converges (to a limit less than or
equal to any bound). This is a fundamental fact about the
real numbers, and is basic to series convergence tests.
SERIES OF REAL NUMBERS
• Series. A series is a sequence obtained by adding the
N
values of another sequence
/ a n =a0+...+aN. The value
n=0
of the series at N is the sum of values up to aN and is called
N
a partial sum:
3
/ a n=a0+...+ aN.
The series itself is
n=0
/ a n . The an are called the terms of the series.
3
n=0
• Convergence. A series / a n converges if the sequence of
denoted
n=0
partial sums converges, in which case the limit of the
sequence of partial sums is called the sum of the series.
If the series converges, the notation for the series itself
stands also for its sum:
3
N
n=0
n=0
/ a n =Nlim
/ an .
"3
Calculus 2.qxd
12/6/07
1:46 PM
Page 3
INTEGRATION FORMULAS
• Basic indefinite integrals. Each formula gives just one
antiderivative (all others differing by a constant from that
given), and is valid on any open interval where the
integrand is defined:
n+1
# x n dx= nx+1 ]n! 1g
# x1 dx=ln x
n
kx
#e kx dx= ek ]k!0g
#a x dx= lna a ]a!1g
#cos x dx=sin x
dx =arctan x
#1+
x2
#sin x dx= cos x
# dx 2 =arcsin x
1x
• Further indefinite integrals. The above conventions hold:
#cot x dx=ln sin x
#tan x dx=ln sec x
#sec x dx=ln sec x+tan x
#csc x dx=ln csc x+cot x
#cosh x dx=sinh x
#sinh x dx=cosh x
= 1 ln xa
# x 2dx
# x dx= 12 x x
a 2 2a x+a
dx =ln x+ x 2 +a 2 =sinh 1 x +ln a
a
x 2 +a 2
# dx2 2 =ln x+ x 2 a 2 cosh 1 ax +ln a
x a
(take positive values for cosh1)
2
# x 2 !a 2 dx= 12 x x 2 a 2 ! a2 ln x+ x 2 !a 2
(Take same sign, + or –, throughout)
2
# a 2 x 2 dx= 12 x a 2 x 2 + a2 arcsin ax
• Common definite integrals:
2
1
¹
1
#0 x n dx= n+
# r r 2x 2 dx= ¹4r #0 sin x dx=2
1 0
¹/2
¹/ 2
2θ dθ= ¹
#0 cos 2 θdθ= #0 1+cos
4
2
¹/2
¹/2
2θ dθ= ¹
#0 sin 2 θdθ= #0 1cos
4
2
θ ) equals cos2θ or
To remember which of 1/2 (1± cos 2θ
sin2θ, recall the value at zero.
#
Other routine integrationbyparts integrands are arcsin x,
ln x, x n ln x, x sin x, x cos x, and xe ax.
• Rational functions. Every rational function may be
written as a polynomial plus a proper rational function
(degree of numerator less than degree of denominator). A
proper rational function with real coefficients has a partial
fraction decomposition: It can be written as a sum with
each summand being either a constant over a power of a
linear polynomial or a linear polynomial over a power of a
quadratic. A factor (x– c) k in the denominator of the
rational function implies there could be summands
Ak
A1
xc +f+ ] xc g k .
A factor (x2 +bx +c)k (the quadratic not having real roots)
in the denominator implies there could be summands
A k +B k x
A 1 +B 1 x
+f+
.
x 2 +bx+c
] x 2 +bx+c g k
Math software can handle the work, but the following case
1
= C + D
should be familiar. If a ≠ b,
] xa g ] xb g xa xb
where C, D are seen to be C= D= 1 .
ab
1
dx= 1 ^ ln xa ln xb h .
Thus #
] xa g ] xb g
ab
In general, the indefinite integral of a proper rational function
can be broken down via partial fraction decomposition and
linear substitutions (of form u = ax+b) into the integrals
#u 1 du, #u n du ]n21g, #u ]u 2 +1gn du (handled with
n
substitution w = u2 +1), and #] u 2 +1 g du (handled with
substitution u = tan t ).
• Substitution. Refers to the Change of variable formula
(see the Theory section), but often the formula is used in
reverse. For an integral recognized to have the form
#a F ^ g ] xgh gl ] xg dx (with F and g' continuous), you can put
b
u=g (x), du=g'(x)dx, and modify the limits of integration
appropriately:
g ]bg
#a F ^ g ] xgh gl ] xg dx= #g ]ag F ]ug du.
b
In effect, the integral is over a path on the uaxis traced out
by the function g. (If g(b) = g(a) [the path returns to its
start], then the integral is zero.) E.g., u=1+x 2 yields
1
1
#0 = 1+xx 2 dx= 12 #0 1+1x 2 2 x dx= 12 ln ]1+x 2g .
Substitution may be used for indefinite integrals.
= 1 ln u= 1 ln ] 1+x 2 g .
E.g., # x 2 dx= 1 # du
2 u
2
2
1+x
Some general formulas are:
n+1
# g ] xgn gl ] xg dx= gn] x+g 1 , # ggl]]xxgg dx=ln g ] xg ,
IMPROPER INTEGRALS
b
b
b
b
#a u dv=uv ba  #a v du.
For indefinite integration, #u dv=uv #v du.
The common formula is
The procedure is used in derivations where the functions
are general, as well as in explicit integrations. You don’t
need to use “u” and “v.” View the integrand as a product
with one factor to be integrated and the other to be
differentiated; the integral is the integrated factor times the
one to be differentiated, minus the integral of the product
of the two new quantities. The factor to be integrated may
be 1 (giving v = x).
E.g., #arctan x dx=x arctan x # x 2 dx
1+x
APPLICATIONS
∞] and integrable
• Unbounded limits. If f is defined on [a,∞
on [a,B] for all B> a, then
#a
f ] x g dx = lim
provided the limit exists.
E.g.,
#0
3 x
e
dx= lim ] 1e
def
3
B
B"3
#
f ] x g dx
B
B"3 a
• Areas of plane regions. Consider a plane region admitting
an axis such that sections perpendicular to the axis vary in
length according to a known function L(p), a≤ p≤ b. The
area of a strip of width ∆p perpendicular to the axis at p is
∆A=L( p)∆p, and the total area is A= # L ^ p h dp. E.g.,
b
#33 f ] xg dx = Alim
# cf ] xg dx+Blim
#
"3 c
"3 A
def
f ] x g dx = lim
def
#
c"a + c
f ] x g dx
B
(the
f ] x g dx provided the limit exists. A
b
similar definition holds if the integrand is defined on
2
c
1
1
[a, b). E.g., #
dx=
dx is lim #
c"2 0
0
4x 2
4x 2
lim arcsin b c l= r .
2
2
c"2


Singular Integrand
1
#0
c
1
dx = arcsin c c m "
4  x2
1
a
c
6 g ] x g f ] x g@ dx , provided g(x)≥ f (x) on
[a,b]. Sometimes it is simpler to view a region as bounded
by two graphs “over” the yaxis, in which case the
integration variable is y.
2
If f is not defined at a finite number of points in an interval
[a,b], and is integrable on closed subintervals of open
#a
b
f is defined
as a sum of left and righthand limits of integrals over
appropriate closed subintervals, provided all the limits exist.
1
1
a
E.g., # 13 dx= lim # 13 dx+ lim # 13 dx if the
a"0 1 x
b"0 b x
1 x
limits on the right were to exist. They don’t, so the integral
diverges.
• Examples & bounds.
#1 3x1p dx converges for p >1, diverges otherwise.

+
2
y(t)), a≤t≤b, has length
#C ds= #a
b
xl ] t g 2 +yld ] t g 2 dt .
• Area of a surface of revolution. The surface generated by
revolving a graph y =f(x) between x = a and x = b about the
xaxis has area
#b a 2¹ f ] xg
1+f l ] x g 2 dx . If the
generating curve C is parametrized by ((x(t), y(t)),
a≤t≤b, and is revolved about the x axis, the area is
#C 2¹ yds= #a 2¹ y ] t g
b
xl ] t g 2 +yl ] t g 2 dt .
PHYSICS
• Motion in one dimension. Suppose a variable
displacement x(t) along a line has velocity v(t)=x'(t) and
acceleration a(t)=v'(t). Since v is an antiderivative of a,
the fundamental theorem implies: v(t) = v (t0) +
#t
t
a ] u g du, x ] t g=x ] t 0 g + # v ] u g du. E.g., the height x(t)
t
t0
– g due to gravity. Thus v(t) = v(v0) +
and x(t) = x0 +
#0
t
] u g du = v0 – gt
#0 ^v 0 guh du = x0 + v0t–12 gt 2 .
• Work. If F(x) is a variable force acting along a line
parametrized by x, the approximate work done over a small
displacement ∆x at x is ∆W = F(x)∆x (force times
displacement), and the work done over an interval [a,b] is
W= # F ] x g dx.
b
In a fluid lifting problem, often ∆W = ∆F•h( y), where
h( y) is the lifting height for the “slab” of fluid at y with
crosssectional area A( y) and width ∆y, and the slab’s
weight is ∆F= ρ A( y)∆y, ρ being the fluid’s weightdensity.
a
Then W= # tA ^ y h h ^ y h dy.
b
a
DIFFERENTIAL EQUATIONS
a
b
p
• Volumes of solids.
Consider
a
solid
admitting an axis such
that
crosssections
perpendicular to the
axis vary in area
according to a known
function A( p), a≤ p≤b.
The volume of a slab of
thickness ∆p perpendicular to the axis at p is ∆V = A( p)∆p,
and the total volume is V= # A ^ p h dp. E.g., a pyramid
b
a
having square horizontal crosssections, with bottom side
length s and height h, has crosssectional area
A(z) = [s (1– z / h)]2 at height z. Its volume is thus
2
2
h
V= # s 2 c 1 z m dz= s h .
3
h
0
• Solids of revolution. Consider a solid of revolution
determined by a known radius function r(z), a≤ z≤ b, along
its axis of revolution. The area of the crosssectional
“disk” at z is A(z) = π r(z)2, and the volume is
V= # A ] z g dz= #
b
a
intervals between such points, the integral
a
1+f l ] x g 2 dx . A curve C parametrized by ((x(t),
b
choice of c being arbitrary), provided each integral on the
right converges.
• Singular integrands. If f is defined on (a,b] but not at
x = a and is integrable on closed subintervals of (a,b], then
b
b
#3 f ] xg dx = Alim
# f ] xg dx.
"3 A
In each case, if the limit exists, the improper integral
converges, and otherwise it diverges. For f defined on
(– ∞, ∞) and integrable on every bounded interval,
#a
#a
Planar Area
def
V= #
b
of an object thrown at time t 0 =0 from a height x(0) = x0
with a vertical velocity v(0)=v0 undergoes the acceleration
GEOMETRY
g=1
b
• Arc length. A graph y =f (x) between x= a and x=b has length
0
over [a,b] is
g ] xg
#a u ] xg vl ] xg dx=u ] xg v ] xg ba  #a v ] xg ul ] xg dx.
3/2
E.g., # c x 2 m dx converges since the integrand is
0
1+x
bounded by 1/2 3/2} on [0,1] and is always less than 1/x 3/2.
It
converges
to
a
number
less
than
1 # 3 1 dx= 1 +212.4.
2 3/2 1 x 3/2
2 3/2
3
the area of the region bounded by the graphs of f and g
#e gl ] xg dx=e .
• Integration by parts. Explicitly,
g ] xg
1
a
Likewise, for appropriate f,
TECHNIQUES
1 dx converges for p <1, diverges otherwise.
xp
#2 3 x ]ln1 xg p dx converges for p > 1, diverges otherwise.
1
Note: # dx p = , p >1 converges at
x ] ln x g
] n1 g ] ln x g p1
x= ∞, p = 0 or < 1 diverges at x= ∞.
1
3
E.g., # 12 dx converges to 1 and # 12 dx diverges.
1 x
0 x
The above integrals are useful in comparisons to
establish convergence (or divergence) and to get bounds.
#0
a
¹r ] z g dz.
b
2
If the solid lies between two radii r1(z) and r2(z) at each
point z along the axis of revolution, the crosssections
are “washers,” and the volume is the obvious
difference of volumes like that above. Sometimes
a radial coordinate r, a≤ r≤ b, along an axis
perpendicular to the axis of revolution,
parametrizes the heights h (r) of cylindrical
sections (shells) of the solid parallel to the axis of
revolution. In this case, the area of the shell at r is
A(r) = 2 π r h(r), and the volume of the solid is
V= # A ] r g dr= # 2¹rh ] r g dr.
b
a
b
a
• Examples. A differential equation (DE) was solved in the
item Solution to initial value problem; an example of that
type is in Motion in one dimension. In those, the expression
for the derivative involved only the independent variable. A
basic DE involving the dependent variable is y' =ky. A
general DE where only the first–order derivative appears
and is linear in the dependent variable is y'+ p(t) y = q(t).
Generally more difficult are equations in which the
independent variable appears in a \hlt{nonlinear} way;
e.g., y'= y 2 – x. Common in applications are secondorder
DEs that are linear in the dependent variable; e.g.,
y'' = – k y, x 2 y'' + xy'+ x 2 y = 0.
• Solutions. A solution of a DE on an interval is a function
that is differentiable to the order of the DE and satisfies the
equation on the interval. It is a general solution if it
describes virtually all solutions, if not all. A general
solution to an nth order DE generally involves n constants,
each admitting a range of real values. An initial value
problem (IVP) for an nth order DE includes a specification
of the solution’s value and n–1 derivatives at some point.
Generally in applications, an IVP has a unique solution on
some interval containing the initial value point.
• Basic firstorder linear DE. The equation y' = ky,
dy
dy
rewritten
=ky suggests y =kdt where y =kt + c. In
dt
this way, one finds a solution y = Ce kt. On any open
interval, every solution must have that form, because
y'= ky implies d ^ ye kt h, where ye – k t is constant on the
dt
interval. Thus y = Ce k t (C real) is the general solution. The
unique solution with y(a)= ya is y = ya e k(t– a). The trivial
solution is y≡0, solving any IVP y(a)=0.
• General firstorder linear DE. Consider
y' + p(t) y = q(t ). The solution to the associated
homogeneous equation h'+p(t)h=0(dh/h = –p(t)dt)
with h(a)=1 is h ] t g=exp ;  # p ] u g du E .
t
a
If y is a solution to the original DE, then (y/h)' =q/h,
where y=h #q/h. The solution with y (a) = ya is
y(t)=Ya+;  # q ] u g h ] u g 1 du E .
t
a
APPROXIMATIONS
TAYLOR’S FORMULA
• Taylor polynomials. The nth degree Taylor polynomial of
f at c is Pn(x) = f (c) + f '(c) (x – c) + 1 ! f''(c) (x – c) 2 +...+
2
1 f (n)(c)(x–c) n (provided the derivatives exist). When
n!
c= 0, it’s also called a MacLaurin polynomial.
• Taylor’s formula. Assume f has n+1 continuous
derivatives on open interval and that c is a point in the
interval. Then for any x in the interval, f (x)= Pn (x)+Rn(x),
1
f ]n+1g _ p i • (x–c)n+1 for some ξ
where Rn(x) =
] n+1 g !
between c and x (ξ varying with x). The expression for
Rn(x) is called the Lagrange form of the remainder. E.g.,
the remainders for the MacLaurin polynomials of f (x) =
] 1 g n
l n(1+x), –1< x<1, are Rn(x) =
• x n+1.
] n+1 g _ 1+p i n+1
There is a ξ between 0 and x such that ln(1 + x) =
2
1
.
x x +
2 3 _ 1+p i 3
• Error bounds. As x approaches c, the remainder generally
becomes smaller, and a given Taylor polynomial provides a
better approximation of the function value. With the
assumptions and notation above, if f ]n+1g ] x g is bounded
f ] x g Pn ] x g
by M on the interval, then
n+1
M
≤
for all x in the interval. E.g., for x<1,
xc
] n+1 g !
e x≈1+x+x2/ 2, with error no more than 3 x 3 =0.5 x 3,
3!
because the third derivative of e x is bounded by 3 on (–1,1).
• Big O notation. The statement f (x)=p(x)+ O(xm)
f ] x g p ] x g
→0) means that
(as x→
is bounded near x = 0.
xm
(Some authors require that the limit of this ratio as x
approaches 0 exist.) That is, f (x)–p(x) approaches 0 at
essentially the same rate as x m. E.g., Taylor’s formula
implies f (x)=f (0)≠f ' (0)x + 1 f ''(0)x2 +O (x3) if f has
2
continuous third derivative on an open interval containing
0. E.g., sinx =x + O(x3). [Similar relations can be inferred
from the identities in the item Basic MacLaurin Series.]
• L’Hôpital’s rule. This resolves indeterminate ratios or
b 0 or 3
l . If lim f ] x g = 0 = lim g ] x g and if limlf ] x g = 0
x "a
x "a
x "a
0 3
= limlg ] x g are defined and g(x)≠0, for x near a (but not
x "a
f ] xg
f l ] xg
=0=lim
provided
x"a gl ] x g
g ] xg
the latter limit exists, or is infinite. The rule also holds
when the limits of f and g are infinite. Note that f'(a) and
g'(a) are not required to exist. To resolve an indeterminate
∞ – ∞), try to rewrite it as an indeterminate
difference (∞
ratio and apply L’Hôpital’s rule. To resolve an
indeterminate exponential (00, 1∞,or ∞0), take its logarithm
to get a product and rewrite this as a suitable indeterminate
ratio; apply L’Hôpital’s rule; the exponential of the result
resolves the original indeterminate exponential.
1/x
ln x
For lim x x you get and find limx→
=limx→
=0,
→0
→0
x"0
1/x 2
1/x
x
0
where lim x = e = 1.
necessarily at a), then lim
x "a
x"0
NUMERICAL INTEGRATION
• General notes. Solutions to applied problems often
involve definite integrals that cannot be evaluated easily, if
at all, by finding antiderivatives. Readily available
software using refined algorithms can evaluate many
integrals to needed precision. The following methods for
approximating
#b af ] xg dx are elementary. Throughout, n is
the number of intervals in the underlying regular partition
and h =(b – a)/n.
• Trapezoid rule. The line connecting two points on the
graph of a positive function together with the underlying
interval on the x axis form a trapezoid whose area is the
average of the two function values times the length of the
interval. Adding these areas up over a regular partition
gives the trapezoid rule approximation
3
f ] a g n 1
f ]bg
o h. This is also the
+ / f ] aih g +
2
2
i=1
average of the left sum and right sum for the given partition.
The approximation remains valid if f is not positive.
• Midpoint rule. This evaluates the Riemann sum on a
regular partition with the sampling given by the midpoints
Tn =e
of each interval: M n = / f c a+: i 1 D h m h. Each
2
I=0
summand is the area of a trapezoid whose top is the
tangent line segment through the midpoint.
• Simpson’s rule. The weighted sum 1 T1 + 2 M 1 on the
3
3
interval
[a, b]
yields
Simpson’s
rule
b
a
a
+
b
c f ] a g+4 f b
l+f ] b gm .
S=
6
2
This is also the integral of the Simpson's Rule
quadratic that interpolates the
function at the three points. For
a regular partition of [a, b] into
an even number n = 2m of
a
a+b
b
intervals, a formula is:
2
n1
S 2m=h " f ] a g+ 4 / f ] a g+[2i+1]h+ 2 / f (a+2i•h)+ f ] b g,
3
i=0
i=0
where h = (b – a)/n. Simpson’s rule is exact on cubics.
m1
m1
SEQUENCES & SERIES
SEQUENCES
• Sequences. Sequences are functions whose domains
consist of all integers greater than or equal to some initial
integer, usually 0 or 1. The integer in a sequence at n is
usually denoted with a subscripted symbol like an (rather
than with a functional notation a(n)) and is called a term
of the sequence. A sequence is often referred to with an
expression for its terms, e.g., 1/n (with the domain
understood), in lieu of a fuller notation like:
" 1/n , 3 , or n;" 1/n ^ n=1, 2, f h .
n=1
• Elementary sequences. An arithmetic sequence an has a
common difference d between successive values:
an =an–1 +d=a0 +d·n. It is a sequential version of a linear
function, the common difference in the role of slope. A
geometric sequence, with terms gn, has a common ratio r
between successive values: gn = gn1 r=g0 r n. E.g., 5.0, 2.5,
1.25, 0.625, 0.3125,.... It is a sequential version of an
exponential function, the common ratio in the role of base.
• Convergence. A sequence {an} converges if some number
L (called the limit) satisfies the following: Every ε > 0
admits an N such that an – L< ε for all n≥ N. If a limit L
exists, there is only one; one says {an}converges to L, and
writes an→L, or lim a n =L. If a sequence does not
n"3
converge, it diverges. If a sequence an diverges in such a
way that every M> 0 admits an N such that an >M for all
n≥ N, then one writes an → ∞. E.g., if r<1 then r n→ 0; if
r = 1 then r n → 1; otherwise rn diverges, and if r>1, r n →∞.
• Bounded monotone sequences. An increasing sequence
that is bounded above converges (to a limit less than or
equal to any bound). This is a fundamental fact about the
real numbers, and is basic to series convergence tests.
SERIES OF REAL NUMBERS
• Series. A series is a sequence obtained by adding the
N
values of another sequence
/ a n =a0+...+aN. The value
n=0
of the series at N is the sum of values up to aN and is called
N
a partial sum:
3
/ a n=a0+...+ aN.
The series itself is
n=0
/ a n . The an are called the terms of the series.
3
n=0
• Convergence. A series / a n converges if the sequence of
denoted
n=0
partial sums converges, in which case the limit of the
sequence of partial sums is called the sum of the series.
If the series converges, the notation for the series itself
stands also for its sum:
3
N
n=0
n=0
/ a n =Nlim
/ an .
"3
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1:46 PM
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Series continued
3
/ a n =S means the series converges
and its sum is S. In general statements, / a n may stand for
3
/ a n =S.
An equation such as
n=0
n=0
• Geometric series. A (numerical) geometric series has the
3
form
/ ar n, where r is a real number and a≠ 0. A key identity
n=0
N
n
N+1
] r!1 g . It implies
is / r =1+r +r2 +...+r N=1r
1r
n =0
1 ^ if r <1 h e also / ar n =a b 1 1 lo,
/ r n = 1r
1r
3
3
n=0
n=1
and
that the series diverges if r>1. The series diverges if
r=± 1. The convergence and possible sum of any geometric
series can be determined using the preceding formula.
The pseries and geometric series are often used for
comparisons. Try a “limit” comparison when a series
looks like a pseries, but is not directly comparable to it.
3
sin ^ 1/n 2 h
E.g., / sin ^ 1/n 2 h converges since lim
=1.
n"3
1/n 2
n=K
• Ratio & root tests. Assume an ≠ 0.
a n+1
If lim a <1 or lim a n 1/n <1, then / a n converges
n"3
n"3
n
a n+1
1/n
(absolutely). If lim a >1 or lim a n >1, then
n"3
n"3
n
/ a n diverges. These tests are derived by comparison with
geometric series. The following are useful in applying the
root test: lim n p/n =1 (any p) and lim ] n! g 1/n =3. More
3
/ n1P is called the pseries.
n=1
The pseries diverges if p≤1 and converges if p>1 (by
comparison with harmonic series and the integral test,
3
1 diverges, for the partial
below). The harmonic series / n
n=1
2N
1 $1+ N .
sums are unbounded: / n
2
n=1
• Alternating series. These are series whose terms alternate
in (nonzero) sign. If the terms of an alternating series
strictly decrease in absolute value and approach a limit of
zero, then the series converges. Moreover, the truncation
error is less than the absolute value of the first omitted
/ ] 1 g
3
term:
n
a n  / ] 1 g a n <a N+1 . (assuming
N
n
an → 0 in a strictly decreasing manner).
n=1
n=1
CONVERGENCE TESTS
3
/ a n converges, then
n=K
If a n " 0, then / a n
• Basic considerations. For any K, if
3
/ an
converges, and conversely.
n=1
diverges. (Equivalently, if / a n converges, then an→0). This
3
says nothing about, e.g.,
/ n1 . A series of positive terms is
n=K
an increasing sequence of partial sums; if the sequence of
partial sums is bounded, the series converges. This is the
foundation of all the following criteria for convergence.
• Integral test & estimate. Assume f is continuous,
∞). Then
positive, and decreasing on (K,∞
#K 3f ] xg dx,
if and only if
3
/
converges, then
n=K
f ] n g#
/ f ]ng converges
3
n=K
converges. If the series
N
/
n=K
f ] n g + # f ] x g dx, the
POWER SERIES
• Power series. A power series in x is a sequence of
N
n= 0
3
N
/ 13 . / n13 + #133 x13 dx=1.2018..., the left side
n =1 n
n =1
underestimating the sum with error less than f (N+1).
Integral test
n=0
/ a n ] xcgn =a 0 +a 1 ] xcg +a 2 ] xcg2 +f.
3
n=0
Replacing x with a real number q in a power series yields
a series of real numbers. A power series converges at q if
the resulting series of real numbers converges.
• Interval of convergence. The set of real numbers at which
a power series converges is an interval, called the interval
of convergence, or a point. If the power series is centered
at c, this set is either (i) (– ∞, ∞); (ii) (c – R, c + R) for some
R>0, possibly together with one or both endpoints; or (iii)
the point c alone. In case (ii), R is called the radius of
convergence of the power series, which may be ∞ and 0
for cases (i) and (iii), respectively. Convergence is absolute
for  x– c < R. You can often determine a radius of
convergence by solving the inequality that puts the ratio
(or root) test limit less than 1. E.g., for
3
n +1
n 2
x
x
: 2 nn / <1& x <2,
/ xn 2, nlim
"3 2 n+1 ] n+1 g 2
2
x
n =1 2 n
which, with the ratio test, shows that the radius of
convergence is 2.
• Geometric power series. A power series determines a
function on its interval of convergence:
n
x " f ] x g= / a n ] xc g n . One says the series converges
3
n= 0
3
N
x N+1 ] x!1 g,
/ x n =1+x+x2+…+xN= 11x
n=0
polynomials
converges for x in the interval (–1,1) to 1/(1–x) and
n=0
geometric series may be identified through this basic one.
/ 2:3 n x n =2 x3 / b x3 l
3
E.g.,
3
E.g.,
/ 13
n=1 n
≈
12
/ 13
n=1 n
+
#13
3
1 dx
x3
= 1.2018..., an
underestimate with error <13–3 <5•10– 4.
• Absolute convergence. If / a n converges, that is, if
/ a n {converges absolutely}, then / a n converges, and
3
3
n=1
n =1
/ an # / an . A
n=0
n
= 2x : 1 ,
3 1x/3
for
x/ 3< 1. The interval of convergence is (–3,3).
• Calculus of power series. Consider a function given by a
power series centered at c with radius of convergence R:
N+1
N
/ x n = 11 x ^ x <1h . Other
3
n =0
3
, i.e., the sequence of
n=0
N
3
f (N+1)
/x
to the function. The series
n
series converges conditionally if it
converges, but not absolutely.
• Comparison tests. Assume an , bn >0.
 If / b n converges and either an £bn (n≥ N ) or an / bn
has a limit, then / a n converges.
3
n
ln ] 1+x g= / ] 1 g n+1 xn for x < 1; a remainder
n=1
argument (see below) implies equality for x =1.
• Taylor and MacLaurin series. The Taylor series
about c of an infinitely differentiable function f is
]kg
3
/ f k!]cg ] xcgk= f (c) + f'(c)(x – c) + f l2l!]cg ] xcg2+g.
k=0
If c = 0, it is also called a MacLaurin series. The Taylor
series at x may converge without converging to f (x). It
converges to f (x) if the remainder in Taylor’s formula,
]
g
R n ] x g= 1
f ]n+1g _ p i:] xc g n+1 (ξξ between c and x,
] n+1 g !
ξ varying with x and n), approaches 0 as n → ∞. E.g., the
remainders at x =1 for the MacLaurin polynomials of
ln(1 + x) (in Taylor’s formula above) satisfy
1
# 1 "0,
R n ]1g =
] n+1 g _ 1+p i n+1 n+1
] 1 g n+1
n .
n=1
3
so ln 2= /
• Computing
A power series in x–c (or “centered at c” or “about c”) is written
diverges otherwise. That is,
!n = K f ^nh . !n = K f ^nh + #N + 1 f ^ xh dx
K
/ an xn .
The power series is denoted
3
12
3
/ a n x n ^ N=0, 1, 2, fh .
polynomials in x of the form
right side overestimating the sum with error less than
3
n"3
n"3
1 ] n! g 1/n = 1 .
precisely, nlim
e
"3 n
E.g., / 4n =4 c 1 1 1 m=2.
1 3
n= 1 3
3
• pseries. For p, a real number,
 If / b n diverges and either bn £an (n≥ N ) or an / bn has
a nonzero limit (or approaches ∞), then / a n diverges.
f(x)=
Taylor
series.
/ a n ] xcgn ^ xc <R h,
1 = / nx n1= / ] n+1 g x n ^ x <1 h .
series gives
] 1x g 2 n=1
n=0
• Basic MacLaurin series:
3
3
1 =1+x+x2 + ...= / x n ^ x <1 h
1x
n=0
3
3
n
x 2 + x 3 – ... = /
] 1 g]n+1 g x ] 11x#1 g
n
2 3
n=1
ln 1+x =2 c x+ x
3
1x
3
3
arctan x=x – x
3
+
5
+
x 5 +g m=2 / x 2n+1 ^ x <1 h
5
n=0 2n+1
3
x
5
The differentiated series has radius of convergence R, but
may diverge at an endpoint where the original converged.
Such a function is integrable on (c – R, c + R), and its
integral vanishing at c is:
#c
a
f ] t g dt= / n ] xc g n+1 ^ xc <R h .
n=0 n+1
x
3
4
INTEGRATION
DEFINITIONS
INTERPRETATIONS
• Heuristics. The definite integral captures the idea of
adding the values of a function over a continuum.
• Riemann sum. A suitably weighted sum of values. A
definite integral is the limiting value of such sums. A
Riemann sum of a function f defined on [a, b] is
determined by a partition, which is a finite division of
[a, b] into subintervals, typically expressed by
a = x0< x1···< xn= b; and a sampling of points, one point
from each subinterval, say ci from [xi –1, xi ]. The associated
• Area under a curve. If f is nonnegative and continuous on
Riemann sum is:
g=
A regular partition has subintervals all the same length,
∆ x = (b – a) / n, xi = a + i ∆ x. A partition’s norm is its
maximum subinterval length. A left sum takes the left
endpoint ci = xi –1 of each subinterval; a right sum, the
right endpoint. An upper sum of a continuous f takes a
point ci in each subinterval where the maximum value of f
is achieved; a lower sum, the minimum value. E.g., the
upper Riemann sum of cosx on [0,3] with a regular
partition of n intervals is the left sum (since the cosine is
3 l +1D 3 .
decreasing on the interval): / :cos b]i1g n
n
i=1
n
Riemann sum
2n+1
n=0
1
2
3
• Definite integral. The definite integral of f from a to b
3
2
4
] 1 g n x 2n
cos x=1x+ x + x g= /
] 2n g !
2! 4!
n =0
may be described as
[a, b], then
the area accumulated up to x. If f is negative, the integral
is the negative of the area.
• Average value. The average value of f over an interval [a,b]
b
may be defined by average value = 1 # f ]xgdx.
ba a
A rough estimate of an integral may be made by estimating
the average value (by inspecting the graph) and
multiplying it by the length of the interval. (See Mean
Value Theorem (MVT) for integrals, in the Theory section.)
• Accumulated change. The integral of a rate of change of
a quantity over a time interval gives the total change in the
quantity over the time interval. E.g., if v(t)= s'(t) is a
velocity (the rate of change of position), then v(t)∆t is the
approximate displacement occurring in the time increment
t to t+∆t; adding the displacements for all time increments
gives the approximate change in position over the entire
time interval. In the limit of small time increments, one
gets the exact total displacement:
#a
v ]t gdt=s(b)– s(a).
b
• Integral curve. Imagine that a function f determines a
slope f (x) for each x. Placing line segments with slope
f (x) at points (x, y) for various y, and doing this for various
x, one gets a slope field. An antiderivative of f is a function
whose graph is tangent to the slope field at each point. The
graph of the antiderivative is called an integral curve of
the slope field.
• Solution to initial value problem. The solution to the
differential equation y' = f (x) with initial value y(x0 )=y0 is
Fundamental Theorem
f(x)
f(x)
A(x)
h
a
x
• Differentiation of integrals. Functions are often defined
as integrals. E.g., the “sine integral function” is
x
Si ]xg= # b sin t ldt.
t
0
To differentiate such, use the second part of the
fundamental theorem: Si'(x) = sin x /x. A function
#a f ]t gdt
x2
such as
is a composition involving
A ]ug= # f ]t gdt. To differentiate, use the chain rule
u
a
and the fundamental theorem:
x
d
d A ^x 2h=A’ ^x 2h2x=2xf ^x 2h.
# f ]t gdt= dx
dx a
• Mean value theorem for integrals. If f and g are
continuous on [a,b], then there is a ξ in [a,b] such that
2
#a f ]xgg ]xgdx=f _pi #a g ]xgdx.
b
b
In the case g ≡ 1, the average value of f is attained
b
somewhere on the interval: 1 # f ]xgdx=f _pi.
ba a
]xg=y 0 + # f ]t gdt.
value is denoted
The binomial coefficients are e o=1, e o=p, e o=
p ^ p 1 h
, and (“p choose k ”)
2
p
p ^ p1 h ^ p2 h g ^ pk+1 h
e o=
k!
k
b
p
p
p
0
1
2
#a f ] xg dx or #a f . The function must be
b
b
bounded to be integrable. The function f is called the
integrand and the points a and b are called the lower limit
and upper limit of integration, respectively. The word
integral refers to the formation of
If p is a positive integer, e o= 0 for k > p.
p
k
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Note: Due to its condensed
format, please use this
QuickStudy as a guide, but
not as a replacement for
assigned classwork.
®
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THEORY
i
2n+1
MVT for Integrals
x0
/ f ]c ig Ds i .
#a f ] xg dx= Dlim
x "0
The limit is said to exist if some number S (to be called the
integral) satisfies the following: Every ε > 0 admits a δ
such that all Riemann sums on partitions of [a, b] with
norm less than δ differ from S by less than ε . If there is
such a value S, the function is said to be integrable and the
] 1 g x
sin x=x x + x g= /
] 2n+1 g !
3 ! 5!
n =0
• Binomial series. For p≠ 0, and for x<1,
3 p
p ^ p 1 h 2
] 1+x g p =1+px+
x +g= / e o x k .
2!
n= 0 k
n
3
quickstudy.com
cos ; i  1 E + 1 1
2
2
#b af ]xgdx gives the area between the xaxis
x
and the graph. The area function A ]xg= # f ]t gdt gives
a
A' (x) = f (x) (valid for onesided derivatives at the
endpoints).
x
3
2
n
3
e =1+x+ x + x +g= / x
2! 3!
n=0 n!
free downloads &
hundreds of titles at
!
i =1
1
x
5
6
2
The following hold for all real x:
3
/ f ]c ig ] x i x i1g .
n
^ x #1 h
/ ]1gn 2xn+1
3
n=0
3
then the coefficients are
necessarily the Taylor coefficients: an = f (n)(c) / n!. This
means Taylor series may be found other than by directly
computing coefficients. Differentiating the geometric
Such a function is differentiable on (c– R, c+R), and its
n=1
and
3
n
derivative there is f l ] x g= / na n ] xc g n1 .
R>0
If
n=0
ln(1+x)=x–
INTEGRAL & DIFFERENTIAL CALCULUS FOR ADVANCED STUDENTS
i=1
f ] x g= / a n ] xc g .
3
WORLD’S #1 ACADEMIC OUTLINE
The integrated series has radius of convergence R, and may
converge at an endpoint where the original diverged.
E.g., 1 =1x+x 2 g implies 1 =1x+x 2 g.
1+x
1+x
The initial (geometric) series converges on (–1, 1), and the
integrated series converges on (1, –1). The integration says
• Integrability & inequalities. A continuous function on a
closed interval is integrable. Integrability on [a, b] implies
integrability on closed subintervals of [a, b]. Assuming f is
integrable, if L≤ f (x)≤ M for all x in [a, b], then
L:] ba g# # f ] x g dx#M:] ba g .
b
a
Use this to check integral evaluations with rough
overestimates or underestimates.
b
#a f from f and [a,b], as
well as to the resulting value if there is one.
• Antiderivative. An antiderivative of a function f is a
function A whose derivative is f: A' (x)= f (x) for all x in
some domain (usually an interval). Any two antiderivatives
of a function on an interval differ by a constant (a
consequence of the Mean Value Theorem). E.g., both
1 ] xa g 2 and 1 x 2 ax are antiderivatives of x – a ,
2
2
differing by 1 a 2. The indefinite integral of a function f,
2
denoted #f ] x g dx, is an expression for the family of
antiderivatives on a typical (often unspecified)
interval. E.g., (for x < –1, or for x >1).
# 2x dx= x 2 1 +C.
x 1
The constant C, which may have any real value, is the
constant of integration. (Computer programs, and this
chart, may omit the constant, it being understood by the
knowledgeable user that the given antiderivative is just one
representative of a family.)
Basic Integral Bounds
M
a
b
• Change of variable formula. An integrand and limits of
integration can be changed to make an integral easier to
apprehend or evaluate. In effect, the “area” is smoothly
redistributed without changing the integral’s value. If g is
a function with continuous derivative and f is continuous,
then
#a
b
f ] u g du= # f ^ g ] t gh gl ] t g dt, where c, d are
d
c
points with g(c)= a and g(d )=b.
In practice, substitute u=g (t); compute du=g'(t)dt; and
find what t is when u=a and u=b. E.g., u=sin t effects the
L
a
b
If f is nonnegative, then
#a f ]xgdx is nonnegative.
b
If f is integrable on [a, b], then so is f, and
#a
f ] x g dx # #
b
a
b
f ] x g dx.
f ] x g dx=A ] x g a/ A ] b g A ] a g .
b
b
which becomes
The other part is used to construct antiderivatives:
If f is continuous on [a, b], then the function
A ]xg = # f ]t gdt is an antiderivative of f on [a, b]:
x
a
1
#a
b
#0
1u 2 du= #
r/2
0
r/2
cos 2 t dt, since
1sin 2 t cos t dt,
1sin 2 t =cos t
for 0#t#r/2. The formula is often used in reverse,
starting with
• Fundamental theorem of calculus. One part of the
theorem is used to evaluate integrals: If f is continuous on
[a, b], and A is an antiderivative of f on that interval, then
#a
transformation
#b aF ^ g ] xgh gl ] xg dx. See Techniques on pg. 2.
• Natural logarithm. A rigorous definition is ln x =
#1 x u1 du. The change of variable formula with u=1/t
x1
x 1
1
u du = #1 t t 2 dt =  #1 t dt showing that
ln(1/x) = – ln x. The other elementary properties of the
natural log can likewise be easily derived from this
definition. In this approach, an inverse function is deduced
and is defined to be the natural exponential function.
yields
#1
1/x
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