Question

Approximate the real number solution(s) to the polynomial function f(x) = x3 - 4x2 + x + 6 .
(a) x = -3, x = -1, x = 2
(b) x = 3, x = 1, x = -2
(c) x = 3, x = -1, x = 2
(d) x = -3, x = 1, x = -2
this is my homework question it does not make a bit of sense to me please help.