1. The problem statement, all variables and given/known data I am posting this for another student who I noticed did not have the proof in the problem. Here is what she said. Lets try and help her out. I have been working on the problem below and I am stuck. I am stuck primarily because of the part where is says x=0. If x-0, it should cancel everything out. The derivative of 0 is 0 so will cancel everything out I think, so I am not sure if that is the reasoning and the proof behind it. 2. Relevant equations She had no relevant equations. 3. The attempt at a solution She said: I thought I should start this way, but I am not 100% sure.