Question

решите систему уравнений { x-4y=-42{9x+8 y=62

Answer 1

$left { {{x-4y=-42} atop {9x+8 y=62}} right. left { {{x=4y-42} atop {9x+8 y=62}} right. \ 9(4y-42)+8y=62 \ 36y-378+8y=62 \ 44y=440 \ y=10 \ x-4*10=-42 \ x=-42+40 \ x=-2$