Integration BasicsTopic #19 of 32

Basic Integration Rules

Power rule, constant multiple rule, and sum rule for integrals.

Power Rule for Integration

For n1n \neq -1:

xndx=xn+1n+1+C\int x^n \, dx = \frac{x^{n+1}}{n+1} + C

Special Case: n = -1

x1dx=1xdx=lnx+C\int x^{-1} \, dx = \int \frac{1}{x} \, dx = \ln|x| + C

Constant Multiple Rule

kf(x)dx=kf(x)dx\int k \cdot f(x) \, dx = k \cdot \int f(x) \, dx

Sum and Difference Rule

[f(x)±g(x)]dx=f(x)dx±g(x)dx\int [f(x) \pm g(x)] \, dx = \int f(x) \, dx \pm \int g(x) \, dx

Complete Table of Basic Integrals

Algebraic Functions

IntegralResult
kdx\int k \, dxkx+Ckx + C
xndx\int x^n \, dxxn+1n+1+C\frac{x^{n+1}}{n+1} + C, n1n \neq -1
1xdx\int \frac{1}{x} \, dx$\ln
1ax+bdx\int \frac{1}{ax+b} \, dx$\frac{1}{a}\ln

Exponential Functions

IntegralResult
exdx\int e^x \, dxex+Ce^x + C
eaxdx\int e^{ax} \, dx1aeax+C\frac{1}{a}e^{ax} + C
axdx\int a^x \, dxaxln(a)+C\frac{a^x}{\ln(a)} + C

Trigonometric Functions

IntegralResult
sin(x)dx\int \sin(x) \, dxcos(x)+C-\cos(x) + C
cos(x)dx\int \cos(x) \, dxsin(x)+C\sin(x) + C
tan(x)dx\int \tan(x) \, dx$-\ln
cot(x)dx\int \cot(x) \, dx$\ln
sec(x)dx\int \sec(x) \, dx$\ln
csc(x)dx\int \csc(x) \, dx$-\ln
sec2(x)dx\int \sec^2(x) \, dxtan(x)+C\tan(x) + C
csc2(x)dx\int \csc^2(x) \, dxcot(x)+C-\cot(x) + C
sec(x)tan(x)dx\int \sec(x)\tan(x) \, dxsec(x)+C\sec(x) + C
csc(x)cot(x)dx\int \csc(x)\cot(x) \, dxcsc(x)+C-\csc(x) + C

Inverse Trigonometric Functions

IntegralResult
11x2dx\int \frac{1}{\sqrt{1-x^2}} \, dxarcsin(x)+C\arcsin(x) + C
11+x2dx\int \frac{1}{1+x^2} \, dxarctan(x)+C\arctan(x) + C
1x21dx\int \frac{1}{\sqrt{x^2-1}} \, dx$\text{arcsec}(
1a2x2dx\int \frac{1}{\sqrt{a^2-x^2}} \, dxarcsin(xa)+C\arcsin\left(\frac{x}{a}\right) + C
1a2+x2dx\int \frac{1}{a^2+x^2} \, dx1aarctan(xa)+C\frac{1}{a}\arctan\left(\frac{x}{a}\right) + C

Examples

Example 1: Polynomial

(4x32x2+5x3)dx=x423x3+52x23x+C\int (4x^3 - 2x^2 + 5x - 3) \, dx = x^4 - \frac{2}{3}x^3 + \frac{5}{2}x^2 - 3x + C

Example 2: Radicals

(x+1x)dx=(x1/2+x1/2)dx\int (\sqrt{x} + \frac{1}{\sqrt{x}}) \, dx = \int (x^{1/2} + x^{-1/2}) \, dx

=x3/23/2+x1/21/2+C= \frac{x^{3/2}}{3/2} + \frac{x^{1/2}}{1/2} + C

=23x3/2+2x1/2+C=23xx+2x+C= \frac{2}{3}x^{3/2} + 2x^{1/2} + C = \frac{2}{3}x\sqrt{x} + 2\sqrt{x} + C

Example 3: Rational function

x2+1x2dx=(1+1x2)dx=(1+x2)dx\int \frac{x^2 + 1}{x^2} \, dx = \int \left(1 + \frac{1}{x^2}\right) dx = \int (1 + x^{-2}) \, dx

=x1x+C= x - \frac{1}{x} + C

Example 4: Trig functions

(3sin(x)2cos(x))dx=3cos(x)2sin(x)+C\int (3\sin(x) - 2\cos(x)) \, dx = -3\cos(x) - 2\sin(x) + C

Example 5: Exponentials

(e2x3ex)dx=12e2x3ex+C\int (e^{2x} - 3e^x) \, dx = \frac{1}{2}e^{2x} - 3e^x + C

Example 6: Inverse trig pattern

14+x2dx=122+x2dx=12arctan(x2)+C\int \frac{1}{4 + x^2} \, dx = \int \frac{1}{2^2 + x^2} \, dx = \frac{1}{2}\arctan\left(\frac{x}{2}\right) + C

Example 7: Completing the square

13x2dx=1(3)2x2dx=arcsin(x3)+C\int \frac{1}{\sqrt{3 - x^2}} \, dx = \int \frac{1}{\sqrt{(\sqrt{3})^2 - x^2}} \, dx = \arcsin\left(\frac{x}{\sqrt{3}}\right) + C

Tips

  1. Always include +C+C for indefinite integrals
  2. Check by differentiating your answer
  3. Simplify the integrand before integrating when possible
  4. Watch for patterns that match known formulas