Question

This is a problem of finding the difference quotient:

f(x)=x^2+2x

It says find a) f(x+h)

then find b) f(x+h)-f(x) over h

Answer 1

Expand and simplify
(f(x+h)-f(x))/h
=((x+h)^2+2(x+h) - (x^2+2x))/2h
=...

Answer 2

what is considered the x and what is considered the h in the problem from the top?