Решебник по алгебре 9 класс Мерзляк Задание 739

\[\boxed{\mathbf{739\ (739).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[a_{1}a_{4} = a_{2}^{2}\text{\ \ \ }\]

\[\ если\ \ d = 0 \Longrightarrow \text{\ \ }a_{1} \cdot\]

\[\cdot \left( a_{1} + 3d \right) =\]

\[= \left( a_{1} + d \right)^{2} \Longrightarrow \text{\ \ }a_{1}^{2} = a_{1}^{2}\]

\[если\ \ a_{1} = d \Longrightarrow \text{\ \ }a_{1}\left( a_{1} + 3d \right) =\]

\[= \left( a_{1} + d \right)^{2}\]

\[d \cdot (d + 3d) = (d + d)^{2}\text{\ \ }\]

\[d \cdot 4d = (2d)^{2}\text{\ \ }\]

\[4d^{2} = 4d^{2}\ \]

\[Ответ:если\ d = 0\ \ или\]

\[\text{\ \ }a_{1} = d.\]