1. The problem statement, all variables and given/known data http://i.imgur.com/In40pGm.png Answer: C 2. Relevant equations f'(x)=slope=(y1-y2)/(x1-x2) 3. The attempt at a solution I can't even list a valid formula for that... like I tried to integrate f'(x), but f(x) is with y so I don't think I am thinking in the right direction. What are the steps in order to get the correct answer? Thank you very much.