Algebra and Trigonometry 10th Edition

(a) $\frac{\log16}{\log5}$ (a) $\frac{\ln16}{\ln5}$
Just apply the Change-of-Base Formula: $\log_ax=\frac{\log x}{\log a}~or~\log_ax=\frac{\ln x}{\ln a}$. (a) $\log_516=\frac{\log16}{\log5}$ (a) $\log_516=\frac{\ln16}{\ln5}$