Question

Can someone please help with the last problem

Answer 1

18x +9h

Explanation:

Such problems are tedious, but not difficult. The trick is to avoid making mistakes in the algebra.

`(f(x+h)-f(x))/(h)=((9(x+h)^2)-(9x^2))/(h)\\\\=(9(x^2+2xh+h^2)-9x^2)/(h)=(18xh+9h^2)/(h)=\boxed{18x+9h}`