1. The problem statement, all variables and given/known data There's a problem that involves triple integrals, but basically, I've boiled all of it down to the following single integral but cannot proceed any further. ∫u2 sqrt(a2-u2) du from 0 to a where a is a constant 2. Relevant equations 3. The attempt at a solution I attempted to use a change of variables, where v = a2 - u2 and dv = -2udu but i still can't integrate it after substituting in for all u's.