Question

3x+y=-1 x-xy=8

Answer 1

$left { {3x+y=-1} atop {x-xy=8}} right. \ \ left { {y=-1-3x} atop {x(1-y)=8}} right. \ \ left { {y=-1-3x} atop {x(1+1+3x)=8}} right. \ \left { {y=-1-3x} atop {x(2+3x)=8}} right. \ \ 3 x^{2}+2x -8=0 \ \ D=4+4*3*8=100 \ \ x_{1}= frac{-2+10}{2*3}= frac{4}{3} ~~ y_1=-1-3* frac{4}{3}= -5 \ \ x_2= frac{-2-10}{6}=-2 ~~y_2=-1-3*(-2)=5$
Ответ (4/3; -5), (-2; 5)