Решите систему уравнений 5x-3y=21; 3x+2y=5.

\[\left\{ \begin{matrix}
5x - 3y = 21\ \ \ | \cdot 2 \\
3x + 2y = 5\ \ \ \ \ | \cdot 3 \\
\end{matrix} \right.\ \]

\[\left\{ \begin{matrix}
10x - 6y = 42 \\
9x + 6y = 15\ \ \\
\end{matrix} \right.\ ( + )\]

\[19x = 57\]

\[x = 3.\]

\[\left\{ \begin{matrix}
x = 3\ \ \ \ \ \ \ \ \ \ \ \ \ \\
2y = 5 - 3x \\
\end{matrix} \right.\ \Longrightarrow \left\{ \begin{matrix}
x = 3\ \ \ \ \ \ \ \ \ \ \\
2y = 5 - 9 \\
\end{matrix} \right.\ \]

\[\left\{ \begin{matrix}
x = 3\ \ \ \ \ \ \\
2y = - 4 \\
\end{matrix} \right.\ \Longrightarrow \left\{ \begin{matrix}
x = 3\ \ \ \\
y = - 2 \\
\end{matrix} \right.\ \]

\[Ответ:(3;\ - 2).\]