Question

If (x-2) is a factor of x^3+kx^2 +12x-8 then k=?

Answer 1

k = - 6

Explanation:

Since (x - 2) is a factor then x = 2 is a root

Substitute x = 2 into the polynomial and equate to zero, that is

2³ + k(2)² + 12(2) - 8 = 0

8 + 4k + 24 - 8 = 0

4k + 24 = 0 ( subtract 24 from both sides )

4k = - 24 ( divide both sides by 4 )

k = - 6