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