4 256 - x
256 - x^4
1*(x + 4)*(x - 4)*(x + 4*I)*(x - 4*I)
(((1*(x + 4))*(x - 4))*(x + 4*i))*(x - 4*i)
/ 2\ -(-4 + x)*(4 + x)*\16 + x /
-(-4 + x)*(4 + x)*(16 + x^2)
256.0 - x^4