Primitive of Reciprocal of x by Root of Power of x plus Power of a

Theorem

 * $\displaystyle \int \frac {\mathrm d x} {x \sqrt {x^n + a^n} } = \frac 1 {n \sqrt {a^n} } \ln \left({\frac {\sqrt {x^n + a^n} - \sqrt {a^n} } {\sqrt {x^n + a^n} + \sqrt {a^n} } }\right)$