taylor series derative: one-sided formula (f-2-4f-1+3f)/2h

[hunter55]

Using Taylor expansion, show that the one-sided formula (f-2-4f-1+3f)/2h is indeed O(h2). Here f-2, for example, stands for f(xo-2h), and f-1 = f(xo-h), so on.

do the same for

[f(xo+h)-2f(xo)+f(xo)+f(xo-h)]/(h2)

to prove it is O(h2)

Please i need some help i am terribly confused