Mark M. answered 10/30/18
Retired math prof. Very extensive Precalculus tutoring experience.
Since -i is a root, so is i.
A possible polynomial is (-1/2)(x+6)(x+2)(x-i)(x+i)
= (-1/2)(x2+8x+12)(x2+1) = -1/2(x4+x2+8x3+8x+12x2+12)
= (-1/2)x4 - 4x3 - (13/2)x2 - 4x - 6