Primitive of Reciprocal of a x + b by p x + q

Theorem

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