Вопрос:

Ответ:

\[b_{3} = 12;\ \ b_{5} = 48\]

\[b_{5} = b_{3} \cdot q^{2}\]

\[12 \cdot q^{2} = 48\]

\[q^{2} = 48\ :12\]

\[q1^{2} = 4\]

\[q = 2.\]