Table of integrals

From Wikipedia, the free encyclopedia

It has been suggested that this article or section be merged with List of integrals. (Discuss)

Integration is one of the two basic operations in calculus. While differentiation has easy rules by which the derivative of a complicated function can be found by differentiating its simpler component functions, integration does not, so tables of known integrals are often useful.

This page lists some of the most common antiderivatives; a more complete list can be found in the list of integrals.

We use C for an arbitrary constant of integration that can only be determined if something about the value of the integral at some point is known. Thus each function has an infinite number of antiderivatives.

These formulas only state in another form the assertions in the table of derivatives.

1 Rules for integration of general functions
2 Integrals of simple functions
3 Definite integrals lacking closed-form antiderivatives
- 3.1 The "sophomore's dream"

[edit] Rules for integration of general functions

$\int af(x)\,dx = a\int f(x)\,dx \qquad\mbox{(}a \mbox{ constant)}\,\!$

$\int [f(x) + g(x)]\,dx = \int f(x)\,dx + \int g(x)\,dx$

$\int f(x)g(x)\,dx = f(x)\int g(x)\,dx - \int \left[f'(x) \left(\int g(x)\,dx\right)\right]\,dx$

$\int [f(x)]^n f'(x)\,dx = {[f(x)]^{n+1} \over n+1} + C \qquad\mbox{(for } n\neq -1\mbox{)}\,\!$

$\int {f'(x)\over f(x)}\,dx= \ln{\left|f(x)\right|} + C$

$\int {f'(x) f(x)}\,dx= {1 \over 2} [ f(x) ]^2 + C$

[edit] Integrals of simple functions

[edit] Rational functions

more integrals: List of integrals of rational functions

$\int \,{\rm d}x = x + C$

$\int x^n\,{\rm d}x = \frac{x^{n+1}}{n+1} + C\qquad\mbox{ if }n \ne -1$

$\int {dx \over x} = \ln{\left|x\right|} + C$

$\int {dx \over {a^2+x^2}} = {1 \over a}\arctan {x \over a} + C$

[edit] Irrational functions

more integrals: List of integrals of irrational functions

$\int {dx \over \sqrt{a^2-x^2}} = \sin^{-1} {x \over a} + C$

$\int {-dx \over \sqrt{a^2-x^2}} = \cos^{-1} {x \over a} + C$

$\int {dx \over x \sqrt{x^2-a^2}} = {1 \over a} \sec^{-1} {|x| \over a} + C$

[edit] Logarithms

more integrals: List of integrals of logarithmic functions

$\int \ln {x}\,dx = x \ln {x} - x + C$

$\int \log_b {x}\,dx = x\log_b {x} - x\log_b {e} + C$

[edit] Exponential functions

more integrals: List of integrals of exponential functions

$\int e^x\,dx = e^x + C$

$\int a^x\,dx = \frac{a^x}{\ln{a}} + C$

[edit] Trigonometric functions

more integrals: List of integrals of trigonometric functions and List of integrals of arc functions

$\int \sin{x}\, dx = -\cos{x} + C$

$\int \cos{x}\, dx = \sin{x} + C$

$\int \tan{x} \, dx = -\ln{\left| \cos {x} \right|} + C$

$\int \cot{x} \, dx = \ln{\left| \sin{x} \right|} + C$

$\int \sec{x} \, dx = \ln{\left| \sec{x} + \tan{x}\right|} + C$

$\int \csc{x} \, dx = \ln{\left| \csc{x} - \cot{x}\right|} + C$

$\int \sec^2 x \, dx = \tan x + C$

$\int \csc^2 x \, dx = -\cot x + C$

$\int \sec{x} \, \tan{x} \, dx = \sec{x} + C$

$\int \csc{x} \, \cot{x} \, dx = - \csc{x} + C$

$\int \sin^2 x \, dx = \frac{1}{2}(x - \sin x \cos x) + C$

$\int \cos^2 x \, dx = \frac{1}{2}(x + \sin x \cos x) + C$

$\int \sin^n x \, dx = - \frac{\sin^{n-1} {x} \cos {x}}{n} + \frac{n-1}{n} \int \sin^{n-2}{x} \, dx$

$\int \cos^n x \, dx = \frac{\cos^{n-1} {x} \sin {x}}{n} + \frac{n-1}{n} \int \cos^{n-2}{x} \, dx$

$\int \arctan{x} \, dx = x \, \arctan{x} - \frac{1}{2} \ln{\left| 1 + x^2\right|} + C$

[edit] Hyperbolic functions

more integrals: List of integrals of hyperbolic functions

$\int \sinh x \, dx = \cosh x + C$

$\int \cosh x \, dx = \sinh x + C$

$\int \tanh x \, dx = \ln |\cosh x| + C$

$\int \mbox{csch}\,x \, dx = \ln\left| \tanh {x \over2}\right| + C$

$\int \mbox{sech}\,x \, dx = \arctan(\sinh x) + C$

$\int \coth x \, dx = \ln|\sinh x| + C$

[edit] Inverse hyperbolic functions

$\int \sinh^{-1} x \, dx = x \sinh^{-1} x - \sqrt{x^2+1} + C$

$\int \cosh^{-1} x \, dx = x \cosh^{-1} x+ \sqrt{x^2-1} + C$

$\int \tanh^{-1} x \, dx = x \tanh^{-1} x+ \frac{1}{2}\log{(1-x^2)} + C$

$\int \mbox{csch}^{-1}\,x \, dx = x \mbox{csch}^{-1}\ x+ \log{\left[x\left(\sqrt{1+\frac{1}{x^2}} + 1\right)\right]} + C$

$\int \mbox{sech}^{-1}\,x \, dx = x \mbox{sech}^{-1}\ x- \tan^{-1}{\left(\frac{x}{x-1}\sqrt{\frac{1-x}{1+x}}\right)} + C$

$\int \coth^{-1} x \, dx = x \coth^{-1} x+ \frac{1}{2}\log{(x^2-1)} + C$

[edit] Definite integrals lacking closed-form antiderivatives

There are some functions whose antiderivatives cannot be expressed in closed form. However, the values of the definite integrals of some of these functions over some common intervals can be calculated. A few useful integrals are given below.

$\int_0^\infty{\sqrt{x}\,e^{-x}\,dx} = \frac{1}{2}\sqrt \pi$ (see also Gamma function)

$\int_0^\infty{e^{-x^2}\,dx} = \frac{1}{2}\sqrt \pi$ (the Gaussian integral)

$\int_0^\infty{\frac{x}{e^x-1}\,dx} = \frac{\pi^2}{6}$ (see also Bernoulli number)

$\int_0^\infty{\frac{x^3}{e^x-1}\,dx} = \frac{\pi^4}{15}$

$\int_0^\infty\frac{\sin(x)}{x}\,dx=\frac{\pi}{2}$

$\int_0^\frac{\pi}{2}\sin^n{x}\,dx=\int_0^\frac{\pi}{2}\cos^n{x}\,dx=\frac{1 \cdot 3 \cdot 5 \cdot \cdots \cdot (n-1)}{2 \cdot 4 \cdot 6 \cdot \cdots \cdot n}\frac{\pi}{2}$ (if n is an even integer and $\scriptstyle{n \ge 2}$ )

$\int_0^\frac{\pi}{2}\sin^n{x}\,dx=\int_0^\frac{\pi}{2}\cos^n{x}\,dx=\frac{2 \cdot 4 \cdot 6 \cdot \cdots \cdot (n-1)}{3 \cdot 5 \cdot 7 \cdot \cdots \cdot n}$ (if $\scriptstyle{n}$ is an odd integer and $\scriptstyle{n \ge 3}$ )

$\int_0^\infty x^{z-1}\,e^{-x}\,dx = \Gamma(z)$ (where

Γ(z)

is the Gamma function)

$\int_{-\infty}^\infty e^{-(ax^2+bx+c)}\,dx=\sqrt{\frac{\pi}{a}}\exp\left[\frac{b^2-4ac}{4a}\right]$ (where

exp[u]

is the exponential function

e u

$\int_{0}^{2 \pi} e^{x \cos \theta} d \theta = 2 \pi I_{0}(x)$ (where

I 0 (x)

is the modified Bessel function of the first kind)

$\int_{0}^{2 \pi} e^{x \cos \theta + y \sin \theta} d \theta = 2 \pi I_{0} \sqrt{x^2 + y^2}$

$\int_{-\infty}^{\infty}{(1 + x^2/\nu)^{-(\nu + 1)/2}dx} = \frac { \sqrt{\nu \pi} \ \Gamma(\nu/2)} {\Gamma((\nu + 1)/2))}\,$ ( $\nu > 0\,$ , this is related to the probability density function of the Student's t-distribution)

The method of exhaustion provides a formula for the general case when no antiderivative exists:

$\int_a^b{f(x)\,dx} = (b - a) \sum\limits_{n = 1}^\infty {\sum\limits_{m = 1}^{2^n - 1} {\left( { - 1} \right)^{m + 1} } } 2^{ - n} f(a + m\left( {b - a} \right)2^{-n} )$