let f(x) = 5xˆ2. Determine the value of x such that the average rate of change of f(x) from 3 to x is 55

Question

let f(x) = 5xˆ2. Determine the value of x such that the average rate of change of f(x) from 3 to x is 55

Answer 1

[f(x) - f(3)] / (x - 3 ) = 55

[5x² - 45] / (x - 3) = 55

5x² - 45 = 55x - 165

5x² - 55x + 120 = 0

x² - 11x + 24 = 0

Solve for x.