\[(2,5)^{2} = 6,25;\ \ \ \ \ 6^{2} = 36.\]
\[\left( \sqrt{5} \right)^{2} = 25;\ \ \left( \sqrt{12} \right)^{2} = 12;\ \ \]
\[\ \left( \sqrt{15} \right)^{2} = 15;\ \ \ \left( \sqrt{36} \right)^{2} = 36\]
\[\sqrt{36} \in \lbrack 2,5;6\rbrack\]