\[\boxed{\mathbf{846\ (846).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[b_{2} = 6\]
\[b_{2}^{2} = b_{1}b_{3}\ \]
\[Тогда:\ \ \ \]
\[b_{1}b_{2}b_{3} = b_{2}^{2} \cdot b_{2} = 6^{2} \cdot 6 =\]
\[= 6^{3} = 216.\]
\[Ответ:216.\]