(x-a+1)^4*y^2
1
(x-a-1)*(x-a+1)^3*(-2*a-2)^2
(x-a-1)^2*(x-a+1)^2*(-2*a-2)*(-2*a+2)
-2
-(x-a-1)^2*(x-a+1)^2*y^2
2
(x-a-1)^3*(x-a+1)*(-2*a+2)^2
(x-a-1)^4*y^2