Integrating Algebraic Fractions

Integrating Algebraic Fractions

Algebraic fractions

For an integral containing \(\dfrac{\mathrm{f}(x)}{\mathrm{g}(x)}\) or \(\dfrac{\mathrm{f}(x)}{\sqrt{\mathrm{g}(x)}}\), inspect the denominator and numerator before choosing a decomposition.

  1. If \(\deg \mathrm{f}\geq\deg \mathrm{g}\), perform polynomial long division first.
  2. If the numerator is constant and \(\mathrm{g}(x)\) is quadratic, complete the square and match an MF27 form.
  3. If \(\mathrm{g}(x)\) factorises, express the proper fraction in partial fractions.
  4. If the earlier routes do not apply, try \(\mathrm{f}(x)=A\mathrm{g}'(x)+B\) and split the integral.

Quadratic-denominator reference forms

MF27 denominator formMF27 denominator form
\(\dfrac{1}{\sqrt{a^2-x^2}}\)\(\dfrac{1}{a^2+x^2}\)
\(\dfrac{1}{a^2-x^2}\)\(\dfrac{1}{x^2-a^2}\)

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