#### Answer

NOT a solution
The given equation does not have any real solution because the left side of the equal sign will always be a non negative number. This will never equal the negative value at the right.

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
Substitute the given value for $x$ in the given equation, $
\sqrt{x}=-3
.$ If the left side of the equation becomes equal to the right side of the equation, then the given value of $x$ is a solution to the equation.
$\bf{\text{Solution Details:}}$
Substituting $x$ with $
9
$ in the given equation results to
\begin{array}{l}\require{cancel}
\sqrt{9}=-3
\\\\
3=-3
\text{ (FALSE)}
.\end{array}
Hence, $x=
9
$ is NOT a solution to the given equation.