\(\left(1-xy+y\right)\left(2x+y\right)+xy\left(2x+y-2\right)\)
\(=2x+y-2x^2y-xy^2+2xy+y^2+2x^2y+xy^2-2xy\)
\(=2x+y+y^2\)
Ta có \(VP = ( 1 - xy + y) .(2x +y) + xy (2x + y -2)\)
= \(2x + y - 2x^{2}y - xy^{2} + 2xy + y^{2} + 2x^{2}y + xy^{2} - 2xy\)
= \(2x + y ^{2} + y = VT\)