Answer:
x^3 - 2x^2 - 11x +12
Explanation:
If 1 is a root, then x-1 is a factor
If -3 is a root, then x+3 is a factor
If 4 is a root, then also x-4 is a factor
A product of the three factors gives us the polynomial
(x-1)(x+3)(x-4) = (x^2 +2x - 3)(x-4)
= x^3 - 2x^2 - 11x +12