2 x - x + 1 ---------- 2 x + x + 1
(x^2 - x + 1)/(x^2 + x + 1)
1 - 2*x/(1 + x + x^2)
2*x 1 - ---------- 2 1 + x + x
2 1 + x - x ---------- 2 1 + x + x
(1 + x^2 - x)/(1 + x + x^2)
(1.0 + x^2 - x)/(1.0 + x + x^2)
1 + x*(-1 + x) -------------- 1 + x*(1 + x)
(1 + x*(-1 + x))/(1 + x*(1 + x))