Answer
-$\sqrt 2$
Work Step by Step
Let's assume that reciprocal of -$\frac{1}{\sqrt 2}$ is '$ x$'.
By definition, product of a number and its reciprocal is always 1. Therefore-
$ -(\frac{1}{\sqrt 2})\times x $ = 1
$x$ = $\frac{1}{-(\frac{1}{\sqrt 2})}$
or $ x$ = -$\sqrt 2$
i.e. reciprocal of -$\frac{1}{\sqrt 2}$ is -$\sqrt 2$
