Question

 Решите систему линейных уравнений

$left { {{2x+3(x+y)=11} atop {7(x+3y)-6x=-59}} right.$

Answer 1

$left { {{2x+3x+3y=11} atop {7x+21y-6x=-59}} right. left { {{5x+3y=11} atop {x+21y=-59}} right.$

x=-59-21y

5(-59-21y)+3y=11

-295-105y+3y=11

-295-102y=11

-102y=11+295

-102y=306

y=-3

5x+3*(-3)=11

5x-9=11

5x=11+9

5x=20

x=4

ответ:y=-3;x=4