[tex]
\sqrt{9}=3\notin\mathbb{I} \\
\sqrt{12}=2\sqrt{3}\in\mathbb{I} \\
\sqrt{16}=4\notin\mathbb{I} \\
\sqrt{20}=2\sqrt{5}\in\mathbb{I} \\
\sqrt{25}=5\notin\mathbb{I}
[/tex]
Hope this helps.
