# How to Solve Compound Functions Where the Inner Function Is *ax* + *b*

Some integrals of compound functions *f** *(*g*(*x*)) are easy to do quickly in Calculus. These include compound functions for which you know how to integrate the outer function *f*, and the inner function *g*(*x*) is of the form *ax* + *b* — that is, it differentiates to a constant.

Here are some examples: