Question

{3x+y=-1 {x-xy=8
какой ответ?

Answer 1

$left { {3x+{y=-1} atop {x-xy=8}} right.; left { {{y=-1-3x} atop {x(1-y)=8}} right.; x(2+3x)=8; 3x^2+2x-8=0; D=4-4*3*(-8)=100=10^2; x=frac{-2pm 10  }{2*3} ;left { {{x_{1}=-2} atop {x_{2}=4/3}} right.$