Question

Решите систему 5x+8y=-1
x+2y=4

Answer 1

$left { {{5x+8y=-1} atop {x+2y=4}} right. \\ left { {{5x+8y=-1} atop {x=4-2y}} right. \\ left { {{5(4-2y)+8y=-1} atop {x=4-2y}} right. \\ left { {{20-10y+8y=-1} atop {x=4-2y}} right. \\ left { {{20-2y=-1} atop {x=4-2y}} right. \\ left { {{-2y=-1-20} atop {x=4-2y}} right. \\ left { {{-2y=-21} atop {x=4-2y}} right. \\ left { {{2y=21} atop {x=4-21}} right. \\ left { {{y=frac{21}{2}} atop {x=-17}} right.$

$left { {{x=-17} atop {y=-10.5}} right.$

Ответ: $(-17; -10.5)$