3
(y + x)*(y - x + 2)
--------------------
4
(x - 1) (2.0 + y - x)^3*(x + y)/(-1.0 + x)^4
3
-(-2 + x - y) *(x + y)
-----------------------
4
(-1 + x) 4 2 3 3 2 2 2 3 3
1 + y - 6*x + 2*x + 4*x + 6*y + 8*y + 12*y - 6*x*y - 6*y*x - 2*x*y + 2*y*x
-1 + -----------------------------------------------------------------------------------
4 3 2
1 + x - 4*x - 4*x + 6*x