Primitive of Reciprocal of x by Root of x squared minus a squared cubed

Theorem

 * $\displaystyle \int \frac {\mathrm d x} {x \left({\sqrt {x^2 - a^2} }\right)^3} = \frac {-1} {a^2 \sqrt {x^2 - a^2} } - \frac 1 {a^3} \operatorname{arcsec} \left\vert{\frac x a}\right\vert + C$

Proof
Let:

Also see

 * Primitive of $\dfrac 1 {x \left({\sqrt {x^2 + a^2} }\right)^3}$
 * Primitive of $\dfrac 1 {x \left({\sqrt {a^2 - x^2} }\right)^3}$