Решение уровнения х+у=1 ху= -6

Решите задачу:

$\left \{ {{y+x=1} \atop {xy=-6}} \right \\ \left \{ {{y=1-x} \atop {x(1-x)=-6}} \right. \\ \left \{ {{y=1-x} \atop {x-x^2+6=0}} \right. \\ x^2-x-6=0 \\ x_{1}=3 \\ x_2 = - 2 \\ \left \{ {{y=1-3} \atop {x=3}} \right. \left \{ {{y=1 + 2} \atop {x=-2}} \right. \\ \left \{ {{y=-2} \atop {x=3}} \right. \left \{ {{y=3} \atop {x=-2}} \right.$