The Limit Definition of the Derivative Let f(2) = - 5x2. Calculate f' (9) by completing the steps below 1. Original Problem Given f(a) = - 5x2 find f' (9) 2. Set up, but do not simplify, the difference f'(9) = lim quotient for f' (9) h -+0 3. Multiply out the numerator to get rid of f'(9) = lim parentheses but do not simplify h -+0 4. Simplify completely but do not take the limit f' (9) = lim h -+0 5. Now take the limit to get your simplified answer f' (9) = Note: In the video they use Ax instead of h, but the process is the same