Ответы и объяснения

2013-09-20T08:13:44+04:00
(x+y)(x-y) \ x(x+y)+(x-y)(x-y) \ x(x-y) +7=x-y \ x +x-y \ x +7=x-y \x+x-y\x +7=x-y+x-y\ x +7=2x-2y \x+7