Answer
$\log_{4}(r^{4})$
Work Step by Step
$3\log_{4}r^{2}-2\log_{4}r=\qquad \color{blue}{\text{ ...apply } \log_{a}x^{r}=r\log_{a}x}$
$=\displaystyle \log_{4}(r^{2})^{3}-\log_{4}r^{2}=\qquad \color{blue}{\text{ ...apply } \log_{a}(\frac{x}{y})=\log_{a}x-\log_{a}y}$
$=\displaystyle \log_{4}[\frac{r^{6}}{r^{2}}]$
$=\log_{4}(r^{4})$
