Question

Решите систему уравнений : 4х – у = 9;
3х + 7у = - 1

Answer 1

$\left \{{y=4x-9}\atop {3x+7y=-1}} \right. \\ 3x+7(4x-9)=-1 \\ 31x=62 \\ x=2 \\ \left \{ {{y=4*2-9 \\ } \atop {x=2}} \right. \\ \left \{ {{y=-1} \atop {x=2}} \right.$