Question

What is the average rate of change of f(x)=x2+x−6 between x=3 and x=9?

Answer 1

13

Explanation:

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

`(f(b)-f(a))/(b-a)`

here [ a, b ] = [ 3, 9 ]

f(b) = f(9) = 9² + 9 - 6 = 84

f(a) = f(3) = 3² + 3 - 6 = 6

average rate of change =
`(84-6)/(9-3)` =
`(78)/(6)` = 13