Question

Решите систему уравнения:
{х+Зу=13,
{7х-4у=-34.

Answer 1

$\left \{ {{x+3y=13} \atop {7x-4y=-34}} \right.$
$\left \{ {{x=13-3y} \atop {7x-4y=-34}} \right.$
$7(13-3y)-4y=-34$
$91-21y-4y+34=0$
$-25y=-125$
$y=5$

$x=13-3*5=-2$
ответ:(5;-2)