4 y - 81
y^4 - 81
(x + 3)*(x - 3)*(x + 3*I)*(x - 3*I)
(((x + 3)*(x - 3))*(x + 3*i))*(x - 3*i)
-81.0 + y^4
/ 2\ (-3 + y)*(3 + y)*\9 + y /
(-3 + y)*(3 + y)*(9 + y^2)