## Precalculus: Mathematics for Calculus, 7th Edition

$\frac{1}{\sqrt (2^3)}$
By definition, $2^{-1.5}$ = $\frac{1}{2^{1.5}}$ = $\frac{1}{2^{\frac{3}{2}}}$ = $\frac{1}{\sqrt (2^3)}$