Question

Can someone help me solve question number 14? I've tried to solve it and got 3426 while the answers in the book say it's 2,6. Can someone pls explain why it's wrong?

Answer 1

the values of x are :

x = 2

x = 6

Answer 2

f(x) = x^3 - 12x^2 + 6x - 8

f'(x) = 3x^2 - 24x + 6 = -30

3x^2 - 24x + 36 = 0

x^2 - 8x + 12 = 0

(x - 2)(x - 6) = 0, so x = 2, 6