
Arturo O. answered 05/16/20
Experienced Physics Teacher for Physics Tutoring
The complex conjugate of complex roots must also be roots, so your minimum set of roots is
7i
-7i
7 - i
7 + i
P(x) = A(x - 7i)(x + 7i)[x - (7 - i)][x - (7 + i)],
where A is real, rational, and A ≠ 0.