Home page for accesible maths 1 1 Further Integration

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1.2 Systematic integration of rational functions

Theorem.

Suppose that f(x)f(x) and g(x)g(x) are polynomials such that we can find the roots of the equation g(x)=0g(x)=0. Then we can find the indefinite integral

f(x)g(x)dx\int{\frac{f(x)}{g(x)}}dx

by division, partial fractions, and substitutions.

This gives a systematic approach to integrating h(x)dx\int h(x)dx, which will be outlined here. The technique involves reduction to special cases that can be dealt with by integration by substitution. The crucial cases to consider are when gg is a linear factor or a quadratic. The outcome involves inverse tangents, logarithms and rational functions.