Step-by-step explanation:
the average rate of change is
(f(x2) - f(x1)) / (x2 - x1)
so, for x = 1 and 2
(4×3² - 4×3¹) / (2 - 1) = 36 - 12 = 24
for x = 3 and 4
(4×3⁴ - 4×3³) / (4 - 3) = 324 - 108 = 216
so the second rate is 216/24 = 9 times greater than the first rate.
