Find a fourth degree polynomial equation with integer coefficients that has the given numbers and roots: 2i and 4-i

First the roots are: 2i, 4-i and their pairs of - 2 and 4+i

therefore the factors are x-2i, x+2i, x-4+i and x-4-i

times there using a method of your choice : (x-2i) (x+2i) (x-4+i) (x-4-i)

to get (x^4) - 8 (x^3) + 21 (x^2) - 32x+68