Question

Решить система уравнений

Answer 1

$left { {{(x-y)(x+y)=91} atop {y+x=-7}} right. ; left { {{-7(x-y)=91} atop {y+x=-7}} right. ;left { {{x-y=-13} atop {y+x=-7}} right. ;left { {{2x=-20} atop {y+x=-7}} right. ;x=-10;y=3$