Question

f(x)=(4x+2)^-1. Find f'(x) using the definition of the derivative

Answer 1

f(x)=(4x+2)^-1
f '(x)=[-1(4x+2)^-2]4
=-4/(4x+2)^2 ans...........

Answer 2

The definition of a derivative says:
\[f'(x)=\lim_{\phi \rightarrow 0}\frac{(4(x+\phi)+2)^{-1}-(4x+2)^{-1}}{\phi}\]
Manipulate it until you can do it by hand. I won't show it here.