CPM Homework Help : PC3 Problem 9-58

Given $f (x) = x^2 + x + 1$ , write an expression for $f \left(x + h\right) − f \left(x\right)$ .

Step:

$f(x + h) − f(x) = ((x + h)^2 + (x + h) + 1) − (x^2 + x + 1)$
Simplify.