Answer
$h^{-1}(x) = \log_9 2x$
Work Step by Step
$h(x) = \frac{1}{2}(9^{x})$
Let $h(x) = y$
$y = \frac{1}{2}(9^{x})$
Swap the $x$ and $y$ variable to find the inverse:
$x = \frac{1}{2}(9^{y})$
$x = \frac{9^{y}}{2}$
$2x = 9^{y}$
$y = \log_9 2x$
$h^{-1}(x) = \log_9 2x$