3 2 x - x - 7*x + 15
x^3 - x^2 - 7*x + 15
3 2 15 + x - x - 7*x
15 + x^3 - x^2 - 7*x
(x + 3)*(x + -2 + I)*(x + -2 - I)
((x + 3)*(x - 2 + i))*(x - 2 - i)
/ 2 \ (3 + x)*\5 + x - 4*x/
(3 + x)*(5 + x^2 - 4*x)
15 + x*(-7 + x*(-1 + x))
15.0 + x^3 - x^2 - 7.0*x