2x(2x+3y)-(x-y)в квадрате

2x(2x+3y)-(x-y)²=4x²+6xy-(x²-2xy+y²)=4x²+6xy-x²+2xy-y²=3x²+8xy-y²

Вроде так:
2x(2x+3y)-(x-y)^2=4x^2+6xy-(x^2+2xy+y^2)=4x^2+6xy-x^2-2xy-y^2=3x^2+4xy-y^2