f(x+h)-f(x) = -2 h x + 6 h + 1 h^2.
Find f'(x).

Question

f(x+h)-f(x) = -2 h x + 6 h + 1 h^2.
Find f'(x).

anonymous · Answer

please help!

psymon · Answer

Well, a derivative is basically the difference quotient as h goes to 0. 

$$\lim_{h \rightarrow 0}\frac{ f(x+h)-f(x) }{ h }$$
So the only thing youre missing from an actual derivative is to divide the whoel thing by h and then make any h's remaining in the equation become 0. The derivative f'(x) is what will be remaining.

anonymous · Answer

oh wow that makes tons of sense.  I just was not thinking about this problem in that way

psymon · Answer

Yeah, not that bad. Difference quotient is like the literal "definition" pf a derivative I guess you could say. So if youre not allowed to use regular derivative rules, you just go to that formula I posted and go fromt here.