You can
put this solution on YOUR website!Both complex and irrational roots come in conjugate pairs. That is, if you have a root of the form

, there must also be a root

. Likewise, if

is a root, then

is also a root.
Your roots are in these forms because

and
A number

is a zero of a polynomial function if and only if

is a factor of the polynomial, so:

are the factors of your minimum (4th) degree polynomial. So get busy multiplying.