How do you find f'(x) using the definition of a derivative for f(x)= 2x^2-x ?

1 Answer
Sep 27, 2015

4x-1
See the explanation.

Explanation:

f'(x)=lim_(h->0) (f(x+h)-f(x))/h

lim_(h->0) (2(x+h)^2-(x+h)-(2x^2-x))/h=

lim_(h->0) (2x^2+4xh+2h^2-x-h-2x^2+x)/h=
lim_(h->0) (4xh+2h^2-h)/h=lim_(h->0) (4x+2h-1)=4x-1