ГДЗ по алгебре 9 класс Макарычев ФГОС Задание 554

\[\boxed{\text{555.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]

\[\textbf{а)}\ c_{5} = 27;\ \ c_{27} = 60:\]

\[\left\{ \begin{matrix} c_{1} + 4d = 27\ \ \\ c_{1} + 26d = 60 \\ \end{matrix} \right.\ \Longrightarrow\]

\[\Longrightarrow \left\{ \begin{matrix} 22d = 33\ \ \ \ \ \\ c_{1} = 27 - 4d \\ \end{matrix} \right.\ \Longrightarrow \left\{ \begin{matrix} d = 1,5\ \\ c_{1} = 21. \\ \end{matrix} \right.\ \]

\[Ответ:d = 1,5;\ \ c_{1} = 21.\]

\[\textbf{б)}\ c_{20} = 0;\ \ c_{66} = - 92:\]

\[\left\{ \begin{matrix} c_{1} + 19d = 0\ \ \ \ \ \ \\ c_{1} + 65d = - 92 \\ \end{matrix} \right.\ \Longrightarrow\]

\[\Longrightarrow \left\{ \begin{matrix} 46d = - 92 \\ c_{1} = - 19d\ \ \\ \end{matrix} \right.\ \Longrightarrow \left\{ \begin{matrix} d = - 2\ \\ c_{1} = 38. \\ \end{matrix} \right.\ \]

\[Ответ:d = - 2;\ \ c_{1} = 38.\]