Question

The minimum value of f(x) = 3x⁴ - 8x³ - 48x+25 on [0, 3] is

A. 16

B. 25

C. -39

D. none of these

Answer 1

Answer is : C. -39

Given: f(x) = 3x⁴ - 8x³ - 48x+25.

F’(x) = 12x³ - 24x² - 48 = 0

F’(x) = 12(x³ - 2x² - 4) = 0

Differentiating again, we get,

F’’(x) = 3x² – 4x = 0

x(3x – 4) = 0

x = 0 or x = 4/3

Putting the value in equation, we get,

f(x) = -39

Hence, C is the correct answer