Answer:
Step-by-step explanation:
To find f(a), replace x with a: f(a)=6−1a+15a^2
To find f(a+h), replace x with (a+h): f(a+h) = 6 -(a + h) + 15(a+h)^2
To find f(a+h)−f(a), expand f(a+h) as given above, and then subtract f(a):
f(a+h)−f(a) = 6 -a - h + 15(a^2 + 2ah + h^2) - [6 - a + 15a^2]
6 - a - h + 15a^2 + 30ah + 15h^2 - [6 - a + 15a^2]
This simplifies to: f(a+h)−f(a) = - h + 30ah + 15h^2
