1. The problem statement, all variables and given/known data Let's say you make the inverse substitution x = 2tan(z) in some integral. Let's say you evaluate the integral get something like like 4sin(z). How do you put z back in terms of x? 2. Relevant equations 3. The attempt at a solution I can do it by saying arctan(x/2) = z, but my teacher said we are not allowed to state the answer that way. I'm not sure how else you would do that...?