Consider the forward difference approx. to f'

f'(0)= f(h)-f(0) / h

Let the error be E = f'(0)- (f(h)-f(0) / h)

Derive a formula for E by Taylor expanding f about x0=0 and using the Remainder thm.

So far I have f(x)=f(x0) + f'(x0)h+f''(x0)h^2 /2 + f'''(c)h^3 /6

So the error will be f'''(c)h^3 /6 for some c in the interval

What do I do now?