Primitives involving Root of x squared plus a squared

Theorem
This page gathers together the primitives of some expressions involving $\sqrt{x^2 + a^2}$.

Also see

 * Primitives involving $\left({\sqrt{x^2 + a^2} }\right)^3$


 * Primitives involving $\sqrt{x^2 - a^2}$
 * Primitives involving $\sqrt{a^2 - x^2}$