Answer
$ \log _{b} 8=1$
Work Step by Step
\[
\begin{array}{c}
\text { Given } \log _{b}2=3, \log _{b} 16=4 \\
\log _{b} 8=?
\end{array}
\]
Using
\[
\log _{b}\left(\frac{m}{n}\right)=\log _{b} m-\log _{b} n
\]
$p u t \quad m=16, \quad n=2$
\[
\begin{array}{l}
\therefore \log _{b}\left(\frac{16}{2}\right)=\log _{b} 16-\log _{b} 2 \\
\Rightarrow \log _{b} 8=4-3 \\
\therefore \log _{b} 8=1
\end{array}
\]
