Question

Find the average rate of change between f(-7) and f(-1) in the function f(x)=x^2+2x -8

Answer 1

Answer:

- 6

Step-by-step explanation:

The average rate of change of f(x) in the closed interval [ a, b ] is

$\frac{f(b)-f(a)}{b-a}$

here [ a, b ] = [ - 7, - 1 ]

f(b) = f(- 1) = (- 1)² + 2(- 1) - 8 = 1 - 2 - 8 = - 9

f(a) = f(- 7) = (- 7)² + 2(- 7) - 8 = 49 - 14 - 8 = 27

Hence

average rate of change = $\frac{-9-27}{-1-(-7)}$ = $\frac{-36}{6}$ = - 6