4 z - 16
z^4 - 1*16
1*(x + 2)*(x - 2)*(x + 2*I)*(x - 2*I)
(((1*(x + 2))*(x - 2))*(x + 2*i))*(x - 2*i)
-16.0 + z^4
/ 2\ (-2 + z)*(2 + z)*\4 + z /
(-2 + z)*(2 + z)*(4 + z^2)