Jim L. answered 06/09/19
Personable, effective English, Math and Science Tutor
There are three factors that combine to create the 3rd level polynomial. The fact that one factor is a complex number implies that its complement is also a factor. Hence the desired polynomial is the product of the three factors that create the roots:
F(x) = (x+3)(x-7+5i)(x-7-5i)
F(x) = x^3 -11x^2 +3x +222