Question

2)
{2х + 9 y = 13;
{x – 3 y = 11?​

Answer 1

Решаем методом подстановки:

$\left \{ {{2x+9y=13} \atop {x-3y=11}} \right. <=>\left \{ {{2x+9y=13} \atop {x=11+3y}} \right. <=> \left \{ {{x=11+3y} \atop {2(11+3y)+9y=13}} \right. <=>\\ \left \{ {{x=11+3y} \atop {22+6y+9y=13}} \right. <=> \left \{ {{x=11+3y} \atop {22+15y=13}} \right. <=> \left \{ {{x=11+3y} \atop {15y=13-22}} \right. <=>\\ \left \{ {{x=11+3y} \atop {15y=-9}} \right. <=> \left \{ {{x=11+3*(-0,6)} \atop {y=-0,6}} \right. <=> \left \{ {{x=9,2} \atop {y=-0,6}} \right.$

Ответ: x=9,2; y=-0,6