Question

Find the average rate of change of f(x) = 4x² – 3 from 3 to 9.

Answer 1

Answer:

44

Step-by-step explanation:

Given:

$f(x) = 4x^2 - 3$

Required:

Average range of change from 3 to 9

SOLUTION:

Step 1:

Find f(3) and f(9):

To find f(3), replace x with 3 in the given function

$f(3) = 4(3)^2 - 3$

$f(3) = 4(9) - 3$

$f(3) = 36 - 3$

$f(3) = 33$

To find f(9), replace x with 9 in the given function

$f(9) = 4(9)^2 - 3$

$f(9) = 4(81) - 3$

$f(9) = 324 - 3$

$f(9) = 321$

Average rate of change = $\frac{f(b) - f(a)}{b - a}$

Where,

$a = 3, f(a) = 33$

$b = 9, f(b) = 321$

Plug in the values into the formula for average rate of change.

$= \frac{321 - 33}{9 - 3}$

$= \frac{288}{6}$

$= 44$

Average rate of change = 44