Question

решите систему уравнений методом сложений -5x+7y=6 2x+7y=76

Answer 1

$left { {{-5x+7y=6,} atop {2x+7y=76;}} right. left { {{5x-7y=-6,} atop {2x+7y=76;}} right.(+) left { {{7x=70,} atop {7y=76-2x;}} right. left { {{x=10,} atop {7y=56;}} right. left { {{x=10,} atop {y=8.}} right.$