Question

решите систему уравнений
(х=2у-8
(х-4у=4

2)
(5у-х=8
(5х-4у=23

Answer 1

1)

$\left \{ {{x=2y-8} \atop {x-4y=4}} \right. \\2y-8-4y=4\\y=-6\\x=2(-6)-8=-20$

2)

$\left \{ {{5y-x=8} \atop {5x-4y=23}} \right. => \left \{ {{x=-8+5y} \atop {5x-4y=23}} \right. \\5(-8+5y)-4y=23\\y=3\\x=-8+5*3 = 7$