Primitive of Reciprocal of x by a x + b squared

Theorem

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