Решите систему уравнений: 2a+3b=10; a-2b=-9.

\[\left\{ \begin{matrix} 2a + 3b = 10\ \ \ \ \ \ \ \ \\ a - 2b = - 9\ \ | \cdot 2 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\left\{ \begin{matrix} 2a + 3b = 10\ \ \ \ \\ 2a - 4b = - 18 \\ \end{matrix} \right.\ ( - )\]

\[7b = 28\]

\[b = 4\]

\[\left\{ \begin{matrix} b = 4\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \\ a = - 9 + 2b \\ \end{matrix} \right.\ \]

\[a = - 9 + 2 \cdot 4 = - 9 + 8 = - 1.\]

\[\left\{ \begin{matrix} b = 4\ \ \ \ \\ a = - 1 \\ \end{matrix} \right.\ \]

\[Ответ:( - 1;4).\]