Решите систему уравнений: 5x+7y=-2; 2x-7y=23.

\[\left\{ \begin{matrix} 5x + 7y = - 2 \\ 2x - 7y = 23\ \\ \end{matrix} \right.\ \ \ \ ( - )\]

\[\text{\ \ \ \ \ \ \ }\overline{\ \ \ \ 7x = 21\ \ \ \ \ \ }\]

\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ x = 3\]

\[\left\{ \begin{matrix} x = 3\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \\ 2 \cdot 3 - 23 = 7y \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ }\]

\[\left\{ \begin{matrix} x = 3\ \ \ \ \ \ \ \\ y = - \frac{17}{7} \\ \end{matrix} \right.\ \]

\[Ответ:\left( 3; - \frac{17}{7} \right)\text{.\ }\]