Question

find tha value of f(x)=x3 where f(x+h)-f(x)/h

so far I got 3x2+3hx+h2/h and got stuck from here.

Answer 1

Perhaps you have
f(x) = x^3 (do you have a typo?)
and you want f'(x) ?

f(x+h) = (x+h)^3 = x^3 + 3 x^2h + 3 xh^2 + h^3

subtract x^3
f(x+h) -f(x) = 3 x^2h + 3 xh^2 + h^3

divide by h

3 x^2 + 3 xh + h^2

let h -->0 for derivative
f'(x) = 3 x^2 (the right answer)

Answer 2

0.3 (3x + 9)>or equal to 1.2 -(x+2)