2х-х(в квадрате)+у(в квадрате)+2у

2x-x^2+y^2+2y=y^2+2y-x^2+2x+1-1=(y^2+2y+1)-(x^2-2x+1)=(y+1)^2-(x-1)^2=(y+x)(y-x+2)

[latex]2x- x^{2} + y^{2} +2y[/latex]=[latex]2(x-y)-( x^{2} - y^{2} )=2(x-y)-(x-y)(x+y)=(x-y)(2-x-y)[/latex]