Question

Find the intervals on which each of the following functions is (a) increasing (b) decreasing.

f(x) = 2x³ - 24x+5

Answer 1

f(x) = 2x³ - 24x+5

f’(x) = 6x² - 24

f’(x) = 6(x² - 4)

= 6(x - 2)(x+2)

Function f(x) is decreasing for x ∈ [-2,2] and increasing in x ∈ (-∞, -2) ∪ (2, ∞)