\[b_{1} = - 96;\ \ b_{2} = - 48;\]
\[q = \frac{- 48}{- 96} = \frac{1}{2};\]
\[b_{8} = b_{1} \cdot q^{7} = - 96 \cdot \left( \frac{1}{2} \right)^{7} =\]
\[= - 96 \cdot \frac{1}{128} = - \frac{3}{4} = - 0,75.\]
\[Ответ:b_{8} = - 0,75.\]