Question

решите системное уровнений y=3x 3x+y=12​

Answer 1

$\left \{ {{y=3x} \atop {3x+y=12}} \right. \\3x+3x=12\\6x=12\\x=2\\\left \{ {{6=3*2} \atop {3*2+6=12}} \right. \\y=6$