Can someone please help me solving the difference quotient?? plz??

Question

i have this problem for precal to solve for the difference quotient.it says

find

f(x+h)-f(x)\h if f(x)= 5/x^2

if anyone can help that would b great! if possible, include the work too..thanks alott..(i have a quiz over this stuff 2morrow.. =[

Answer 1

do what it says

f(x+h) = 5 / [ x+h]²

f(x) = 5 / x²

f(x+h) - f(x) = 5 / [x+h]² - 5 / x²  {now algebra...this is a reason you need to be competent in algebra} = {5 x² - 5 [x+h]² } / {[x+h}² x²} = { -10 xh - 5 h²} / { [x+h]² x²}

[ f(x+h) - f(x) ] / h = { -10x -5h} / { [x+h]² x²}...now what happens as h ----> 0 ??