Решите систему уравнений {x-y=7 {x*y=-10

Решите задачу:

$\left \{ {{x-y=7} \atop {x*y=-10}} \right. \\ x=7+y \\ y(7+y)=-10 \\ y^{2} +7y+10=0 \\ D=49-40=9 \\ \sqrt{D} =3 \\ y _{1} = \frac{-7+3}{2} = \frac{-4}{2} =-2 \\ y _{2} = \frac{-7-3}{2} = \frac{-10}{2} =-5 \\ x_{1} =7-2=5 \\ x_{2} =7-5=2 \\ \left \{ {{x=5} \atop {y=-2}} \right. \left \{ {{x=2} \atop {y=-5}} \right.$