Find the average rate of change

Question

f(x)=x^3-8x+9 a. from -3 to -2
b. from -1 to 5
c. from 5 to 9

A. what is average rate of change of f(x)=x^3-8x+9 from -3 to -2?

B. what is the average rate of change of f(x)-x^3-8x+9 from -1 to 5?

C. what is the average rate of change of f(x)=x^3-8x+9 from 5 to 9?

Please show work

Answer 1

How about if someone shows you how to do one and you do the rest?

The average of f'(x) over an interval a to b is the area under the f'(x) curve, divided by (b - a).

That equals f(b) - f(a), because the area under f'(x) dx is the integral, f(x)

A. f(-2) - f(-3) = -8 +16 +9
-(-27) -24 -9 = ?

Answer 2

a. is the answer -6

Answer 3

That is not what I get adding the numbers I gave you, but maybe I made a mistake.

I get +11