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