Question 1067685
We wish to find [f(x+h) - f(x)]/h, for h very small, and x = 9
Substituting the values in the function we get [(x+h)^2 - (x+h) + 8 - (x^2 - x + 8)]/h
Expand and simplify:
[(x^2 + 2xh + h^2 - x - h + 8 - x^2 + x - 8]/h 
We see that all the x^2 and constant terms drop out and we are left with 
[2xh + h^2 - h]/h -> h + 2x - 1
Substituting x = 9 gives h + 18 - 1. For h very small, this reduces to 17.
Ans: 17