They did this:
How, work the algebra magic, take the limit as h approaches 0 and you have it. The derivative of
Note: I used h instead of . Same thing
http://i43.tinypic.com/2j11mgy.jpg --> problem is here
I only would like to know how they got that from the derivative equation. Can you please show me step by step how you'd go about doing it, using that formula?