Answer
$(\log_2{8})^3\ne 3(\log_2{8})$
Refer to the step-by-step part for the computations.
Work Step by Step
If $a=2$, $x=8$, $r=3$, then $(\log_a {x})^r=(\log_2{8})^3=(\log_2{2^3})^3=3^3=27.$
$r(\log_a {x})=3(\log_2{8})=3(\log_2{2^3})=3\cdot3=9.$
$9\ne27.$
