not too sure about this question at all, i've done the first part but i dont really know what is beiong asked in the other 2 parts, thanks for any help
This is essentially asking you to derive the forward difference method using the Taylor series for $\displaystyle f(x+h)$ about the point $\displaystyle x$.
EDIT: A little more of a hint
$\displaystyle f(x + h) - f(x) = hf'(x) + \frac{h^2}{2}f''(\xi)\qquad \xi \in [x,x+h]$