Question

Which of the following is a root of the polynomial function below?

F(x) = x^3+3x^2 + 4x+12
A. 3
B. 2
C. i
D. -2i

Answer 1

`- 2i`

Explanation:

`f(x) = { * }^(3) + 3 {x}^(2) + 4x + 12 \\ = ( {x}^(3) + 3x^(2)) +(4x + 12) = \\ {x}^(2) (x + 3) + 4(x + 3) = \\ ( {x}^(2) + 4)(x + 3)`