Primitive of x squared over x squared minus a squared squared

Theorem

 * $\displaystyle \int \frac {x^2 \ \mathrm d x} {\left({x^2 - a^2}\right)^2} = \frac {-x} {2 \left({x^2 - a^2}\right)} + \frac 1 {4 a} \ln \left\vert{\frac {x - a} {x + a} }\right\vert + C$