Question

помогите ршить систему уравнений пожалуйста

Answer 1

$left { {{x+y=10} atop {xy=21}} right. left { {{x=10-y} atop {(10-y)y=21}} right. left { {{x=10-y} atop {10y- y^{2} =21}} right. \ y^{2}-10y+21=0 \ left { {{y_{1}+y_{2}=10} atop {y_{1}*y_{2}=21 }} right. left { {{y_{1}=3} atop {y_{2}=7 }} right. \ x_{1}=7; \ x_{2}=3.$
Ответ: (7;3), (3;7).