The function f is differentiable at a. Find $\displaystyle \lim_{h\to 0}\frac{f(a+ph)-f(a-ph)}{h}$

I'd assume its something to do with manipulating the definition $\displaystyle \lim_{h\to 0}\frac{f(a+h)-f(a)}{h}$ but have no idea how.

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- Feb 4th 2010, 12:30 PMvuze88Harder limits
The function f is differentiable at a. Find $\displaystyle \lim_{h\to 0}\frac{f(a+ph)-f(a-ph)}{h}$

I'd assume its something to do with manipulating the definition $\displaystyle \lim_{h\to 0}\frac{f(a+h)-f(a)}{h}$ but have no idea how. - Feb 4th 2010, 05:49 PMfelper
- Feb 4th 2010, 07:23 PMvuze88
so is the answer $\displaystyle 2pf'(a)$

- Feb 5th 2010, 06:15 AMfelper