#### Answer

$log_{b}1000=3$

#### Work Step by Step

From the definition of the logarithmic function on page 456, we know that $b^{y}=x$ is equivalent to $y=log_{b}x$ (for $x\gt0$, $b\gt0$, and $b\ne1$).
Therefore, $b^{3}=1000$ is equivalent to $log_{b}1000=3$ in logarithmic form.