6.8 Find the first term and the common ratio of the geometric progression, given that $b_{4}-b_{2}=-\frac{45}{32}$ and $b_{6}-b_{4}=-\frac{45}{512}$.
6.8 Instruction. Form the system

$$
\left\{\begin{array}{l}
b_{1} q\left(q^{2}-1\right)=-\frac{45}{32} \\
b_{1} q^{3}\left(q^{2}-1\right)=-\frac{45}{512}
\end{array}\right.
$$

from which to find $q$.

Answer: $b_{1}=6, q=\frac{1}{4}$ or $b_{1}=-6, q=-\frac{1}{4}$.