Question

Find a polynomial f(x) of degree 3 with real coefficients and the following zeros.
-4,-2+i

Answer 1

When you're looking for a polynomial with certain specific numbers for zeros, say, a, and b, you simply multiply their linear factors, like so:
(x - a)(x - b)
= x² -(a+b)x + ab

Answer 2

Complex numbers are usually no different, in that if a complex number p+qi is a zero of a polynomial, then [x-(p+qi)] is a factor. However, the thing about complex zeros is that if p+qi is a zero of some polynomial, then so is its conjugate, p-qi.