College Algebra

Question

Please help:

if f(x)=2x²-5x-6

find (f(x+h)-f(x))/h

Answer 1

f(x+h) = 2(x+h)^2 - 5(x+h) - 6

= 2(x^2 + 2xh + h^2) - 5x - 5h - 6

= 2x^2 + 4xh + 2h^2 - 5x - 5h - 6

f(x+h) - f(x) = 4xh + 2h^2 -5h

dividing by h: 4x + 2h - 5 <--- this is the difference quotient