Câu hỏi 169
Encontrar todas la soluciones $(x, y)$ reales del sistema de ecuaciones $$
\left.\begin{array}{c}
x^{2}-x y+y^{2}=7 \\
x^{2} y+x y^{2}=-2
\end{array}\right\}
$$
\left.\begin{array}{c}
x^{2}-x y+y^{2}=7 \\
x^{2} y+x y^{2}=-2
\end{array}\right\}
$$