1. The problem statement, all variables and given/known data This is an Optimization Problem, find the maximum value. P(R)=(E^2*R)/(R+r)^2 2. Relevant equations P'(R)=? 3. The attempt at a solution I have the solution to this problem, and I can solve it, I just don't understand some parts. I tend to think that the derivative of E^2*R = 2ER, like the power rule similar to if I solved x^2*y I would get 2xy. But the derivative of E^2*R is just E^2 and I cannot figure it out. Can someone please explain to me with mathematical proof why the derivative of E^2*R=E^2? Thanks a bunch.