Решебник по алгебре 9 класс Макарычев Задание 891

\[\boxed{\text{891\ (891).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[x_{2} = - 32,\ \ q = - \frac{1}{2},\ \ \]

\[S_{10} = ?\]

\[x_{2} = x_{1} \cdot q,\ \]

\[x_{1} = \frac{x_{2}}{q} = 32 \cdot 2 = 64,\]

\[S_{10} = \frac{x_{1} \cdot \left( q^{10} - 1 \right)}{q - 1} =\]

\[= \frac{64 \cdot \left( \left( - \frac{1}{2} \right)^{10} - 1 \right)}{- \frac{1}{2} - 1\ } =\]

\[= \frac{64 \cdot 1023}{1024} \cdot \frac{2}{3} = \frac{341}{8} = 42\frac{5}{8}.\]

\[\boxed{\text{891.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]

\[\textbf{а)}\ \left\{ \begin{matrix} x² + y² \leq 4 \\ |x| \geq 1\ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \]

\[\textbf{б)}\ \left\{ \begin{matrix} x² + y² \leq 9 \\ |y| \geq 2\ \ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \]