Question

The function f(x) = 9 - x⁵ - x⁷ is decreasing for

Options

• 5 ≤ x ≤ 7

• x ≤ 1

• x ≥ 1

• All values of x

Answer 1

All values of x

Explanation:

f(x) = 9 - x⁵ - x⁷ 

⇒ f'(x) = - 5x⁴ - 7x⁶

⇒ f'(x) < 0 for all values of x.