Q. If $b_n=\left(\frac{1}{5}\right)^{\log _{\sqrt{5}}\left(\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\ldots+\frac{1}{4 \cdot 2^{n-1}}\right)}$, find $\left(\left[\displaystyle\lim _{n \rightarrow \infty}\left(b_n\right)\right]+3\right)$.
Sequences and Series
Solution: