## Algebra: A Combined Approach (4th Edition)

$log_{3}\frac{1}{81}=-4$
We know that if $b\gt0$ and $b\ne1$, then $y=log_{b}x$ is equivalent to $x=b^{y}$ (where $x\gt0$ and $y$ is a real number). Therefore, $3^{-4}=\frac{1}{81}$ can be written as the logarithmic equation $log_{3}\frac{1}{81}=-4$.