Answer
$\dfrac{1}{2\sqrt{2}}$
Work Step by Step
Note that $-1.5=-\frac{3}{2}$ so the given expression can be written as:
$2^{-\frac{3}{2}}$
RECALL:
(i) $\sqrt[n]{a^m} = a^{\frac{m}{n}}$
(ii) $a^{-m} = \dfrac{1}{a^m}, a\ne0$
Use rule (ii) above to obtain:
$=\dfrac{1}{2^{\frac{3}{2}}}$
Use rule (i) above, where m=3 and n=2, to obtain:
$=\dfrac{1}{\sqrt{2^3}}$
Simply the denominator to obtain:
$=\dfrac{1}{\sqrt{2^2 \cdot 2}}
\\=\dfrac{1}{2\sqrt{2}}$
