Решите систему уравнений: x-3y=4; 5x+3y=-1.

\[\left\{ \begin{matrix} x - 3y = 4\ \ | \cdot 5 \\ 5x + 3y = - 1\ \ \ \\ \end{matrix} \right.\ \]

\[\left\{ \begin{matrix} 5x - 15y = 20 \\ 5x + 3y = - 1\ \\ \end{matrix} \right.\ ( - )\]

\[- 18y = 21\]

\[y = - \frac{21}{18} = - \frac{7}{6}\]

\[y = - 1\frac{1}{6};\]

\[x = 4 + 3y = 4 + 3 \cdot \left( - \frac{7}{6} \right) =\]

\[= 4 - \frac{7}{2} = 4 - 3,5 = 0,5.\]

\[Ответ:\left( 0,5;\ - 1\frac{1}{6} \right).\]