Question

(x + y = 6,
xy = -7;​

Answer 1

$\left \{ {{x+y=6} \atop {xy=-7}} \right. =>x=6-y\\\\(6-y)y=-7\\6y-y^2=-7\\y^2-6y-7=0\\D=36+28=64=8^2\\y_1=(6-8)/2=-1\\y_2=(6+8)/2=7\\\\\left \{ {{x_1=6-(-1)} \atop {x_2=6-7}} \right. =>\left \{ {{x_1=7} \atop {x_2=-1}} \right.$

ОТВЕТ: $x_1=7\\x_2=-1\\y_1=-1\\y_2=7$