\[2\sqrt{7}\ и\ 3\sqrt{3}\ \]
\[2\sqrt{7} = \sqrt{4 \bullet 7} = \sqrt{28}\]
\[3\sqrt{3} = \sqrt{9 \cdot 3} = \sqrt{27}\]
\[\sqrt{28} > \sqrt{27}\]
\[\Longrightarrow 2\sqrt{7} > 3\sqrt{3}.\]