3 x - x -------- 3 4*x - x
(x^3 - x)/(-x + 4.0*x^3)
2 -1 + x --------- 2 -1 + 4*x
1 3 - - ---------- 4 2 -4 + 16*x
(1 + x)*(-1 + x) -------------------- (1 + 2*x)*(-1 + 2*x)