Answer
$\dfrac{1}{7}$
Work Step by Step
RECALL:
(i) $a^{-\frac{m}{n}}=\dfrac{1}{a^{\frac{m}{n}}}$
(ii) $a^{\frac{m}{n}}=\sqrt[n]{a^m}$
Use the rule above to obtain:
$=\dfrac{1}{49^{\frac{1}{2}}}
\\=\dfrac{1}{\sqrt{49}}
\\=\dfrac{1}{7}$