Решебник по алгебре и начала математического анализа 11 класс Колягин Задание 938

\[1)\ \left\{ \begin{matrix} 5x - 7y = 3\ \ \\ 6x + 5y = 17 \\ \end{matrix} \right.\ \]

\[5x - 7y = 3\]

\[5x = 7y + 3\]

\[x = 1,4y + 0,6.\]

\[6x + 5y = 17\]

\[6(1,4y + 0,6) + 5y = 17\]

\[8,4y + 3,6 + 5y = 17\]

\[13,4y = 13,4\]

\[y = 1;\]

\[x = 1,4 + 0,6 = 2.\]

\[Ответ:\ \ (2;\ 1).\]

\[2)\ \left\{ \begin{matrix} 2x - y - 13 = 0 \\ x + 2y + 1 = 0\ \ \\ \end{matrix} \right.\ \]

\[2x - y - 13 = 0\]

\[y = 2x - 13.\]

\[x + 2y + 1 = 0\]

\[x + 2(2x - 13) + 1 = 0\]

\[x + 4x - 26 + 1 = 0\]

\[5x = 25\]

\[x = 5;\]

\[y = 10 - 13 = - 3.\]

\[Ответ:\ \ (5;\ - 3).\]