Question

Решите систему уравнений
2x−y=15
x−3y=5

х=?
y=?

Answer 1

$\left \{ {{2x-y=15} \atop {x-3y=5}} \right. \left \{ {{y=-15+2x} \atop {x-3y=5}} \right.\\ \\-3(-15+2x)=5 \\x+45-6x=5 \\-5x+45=5 \\-5x=5-45 \\-5x=-40 \\x=8 \\y=-15+2*8 \\y=-15+16 \\y=1 \\(x,y)=(8,1).$