Find the average rate of change for f(x)=6x+9 over the interval [1,5]. You must simplify your answer.

Question

I need help please ! with an explanation

Answer 1

6 is the rate of change = slope = coefficient of the x term, when the equation is solved for y

at x=1 f(x) = 6(1) + 9 = 15

x=5 f(x) = 6(5) + 9 = 39

[f(5)-f(1)](5-1) = (39-15)/4 = 24/4 = 6