Answer
$\dfrac{11}{18}$
Work Step by Step
Using $a^{-x}=\dfrac{1}{a^x}$, the given expression, $
2^{-1}+3^{-2}
,$ simplifies to
\begin{array}{l}\require{cancel}
\dfrac{1}{2^1}+\dfrac{1}{3^2}
\\\\=
\dfrac{1}{2}+\dfrac{1}{9}
\\\\=
\dfrac{9}{18}+\dfrac{2}{18}
\\\\=
\dfrac{11}{18}
.\end{array}
