f(x)=2x^2-4

Question

f(x+delta x)-f(x)/delta x

solve for the solution

Answer 1

f(x+delta x)-f(x)/delta x
= [2(x+delta x)^2 -4 -2x^2 +4]/(delta x)
= [2x^2 + 4(x delta x +(delta x)^2 -2x^2 +4]/(delta x)
= 4x + delta x
Which becomes 4x when delta x -> 0