Answer
(a) $\frac{\log4}{\log{\frac{1}{5}}}$
(a) $\frac{\ln4}{\ln{\frac{1}{5}}}$
Work Step by Step
Just apply the Change-of-Base Formula: $\log_ax=\frac{\log x}{\log a}~or~\log_ax=\frac{\ln x}{\ln a}$.
(a) $\log_{\frac{1}{5}}4=\frac{\log4}{\log{\frac{1}{5}}}$
(a) $\log_{\frac{1}{5}}4=\frac{\ln4}{\ln{\frac{1}{5}}}$
