1. The problem statement, all variables and given/known data I was given this question as a part of an assignment and lost a mark because of a step. 2. Relevant equations the integral of cos^5(x) dx after some fiddling and substitution it gets to this (1 - u^2)^2 du In the solutions there is a step that says refine = (u^2 - 1)^2 basically switching the the 1 and the u^2 around. 3. The attempt at a solution Is this possible and if so how?