f(x+h)−f(x)=4hx−1h+5h^2.

Question

Find f′(x).

Answer 1

f'(x) = lim (f(x+h)−f(x))/h , as h ---> 0
=lim (4hx−1h+5h^2)/h , as h ---> 0
= Lim (4x - 1 + 5h) , as h ---> 0
= 4x - 1