Question 16724
In step 2, you made the most common error in this type of problem.  When you do f(5+h) - f(5), be sure to minus the quantity of f(5)!!


It should look like this with extra parentheses added:
   f(5+h) - f(5) = 51 + 15h + h^2 - (5^2 + 5(5) + 1)
= 51 + 15h + h^2 - (25 + 25 + 1)
=  15h + h2 
3. f(5+h) - f(5) over h =  (15h + h^2) over h, which comes out to 
 
The teacher's answer which is 15 + h


R^2 at SCC