Вопрос:

Решите систему уравнений: 6=3(x+y); 6-5(x-y)=8x-2y.

Ответ:


\[\left\{ \begin{matrix}
6 = 3 \cdot (x + y)\text{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ } \\
6 - 5 \cdot (x - y) = 8x - 2y \\
\end{matrix} \right.\ \text{\ \ \ \ \ \ \ }\]


\[\left\{ \begin{matrix}
x + y = 2\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \\
6 - 5x + 5y - 8x + 2y = 0 \\
\end{matrix} \right.\ \]


\[\left\{ \begin{matrix}
x + y = 2\ \ \ \ \ \ \ \ \ \ \ \ \\
- 13x + 7y = - 6 \\
\end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ }\]


\[\left\{ \begin{matrix}
x = 2 - y\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \\
- 13 \cdot (2 - y) + 7y = - 6 \\
\end{matrix} \right.\ \text{\ \ \ \ \ \ }\]


\[- 26 + 13y + 7y = - 6\]


\[20y = - 6 + 26\]


\[20y = 20\]


\[y = 1.\]


\[\left\{ \begin{matrix}
y = 1\ \ \ \ \ \ \ \\
x = 2 - 1 \\
\end{matrix} \right.\ \text{\ \ \ \ \ \ }\left\{ \begin{matrix}
y = 1 \\
x = 1 \\
\end{matrix} \right.\ \]


\[Ответ:(1;1).\]


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