1. The problem statement, all variables and given/known data http://imgur.com/MSkNkno 2. Relevant equations 3. The attempt at a solution I know that I would have to take the derivative of H(x) which is G(x)+G'(x)x so then I would need G'(x) which I figured would be f'^-1(x) but I'm not sure about that. Doing that I got a value of 16 which isn't an answer.