Answer
$\frac{1}{a^{\frac{9}{2}}}$
Work Step by Step
$(a^{\frac{1}{2}} \times a^{-2})^{3}$
=$(a^{\frac{1}{2}-2})^{3}$
=$(a^{\frac{1-2(2)}{2}})^{3}$
=$(a^{\frac{1-4}{2}})^{3}$
=$(a^{\frac{-3}{2}})^{3}$
=$a^{-\frac{9}{2}}$
=$\frac{1}{a^{\frac{9}{2}}}$