Найдите первый член и разность арифметической прогрессии (an), если: a3+a5=-2 и a7+a10=4.

\[\left\{ \begin{matrix} a_{3} + a_{5} = - 2 \\ a_{7} + a_{10} = 4\ \ \\ \end{matrix}\text{\ \ \ \ } \right.\ \]

\[\left\{ \begin{matrix} a_{1} + 2d + a_{1} + 4d = - 2 \\ a_{1} + 6d + a_{1} + 9d = 4\ \ \ \\ \end{matrix}\text{\ \ \ \ \ } \right.\ \]

\[\left\{ \begin{matrix} 2a_{1} + 6d = - 2 \\ 2a_{1} + 15d = 4 \\ \end{matrix} \right.\ ( - )\]

\[\left\{ \begin{matrix} - 9d = - 6\ \ \ \ \ \ \\ a_{1} = \frac{- 2 - 6d}{2} \\ \end{matrix}\text{\ \ \ \ \ \ \ \ } \right.\ \text{\ \ }\]

\[\left\{ \begin{matrix} d = \frac{2}{3}\text{\ \ \ \ \ \ } \\ a_{1} = - 3 \\ \end{matrix} \right.\ \]

\[Ответ:\ \ a_{1} = - 3;\ \ d = \frac{2}{3}.\]