3 x - 5*x
x^3 - 5*x
/ ___\ / ___\ 1*(x + 0)*\x + \/ 5 /*\x - \/ 5 /
((1*(x + 0))*(x + sqrt(5)))*(x - sqrt(5))
/ 2\ x*\-5 + x /
x*(-5 + x^2)
x^3 - 5.0*x