4 x - 625
x^4 - 625
(x + 5)*(x - 5)*(x + 5*I)*(x - 5*I)
(((x + 5)*(x - 5))*(x + 5*i))*(x - 5*i)
/ 2\ (-5 + x)*(5 + x)*\25 + x /
(-5 + x)*(5 + x)*(25 + x^2)
-625.0 + x^4