Question

{y+x=0
{yx+y=6 пжпжпжп

Answer 1

$\displaystyle \left \{ {{y+x=0} \atop {yx+y=6}} \right. \\\\\left \{ {{y=-x} \atop {xy+y=6}} \right. \\\\x(-x)+(-x)=6\\x \notin R\\(x,y) \notin R^2$