Разложить на множители: 2(x+y)(x-y)-(x+y)^2.

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

\[= 2(x + y)(x - y) - (x + y)(x + y) =\]

\[= (x + y)(2x - 2y - x - y)(2x - 2y + x + y) =\]

\[= (x + y)(x - 3y)(3x - y).\]