\[18\sqrt{7} - 9\sqrt{28} = 18\sqrt{7} - 18\sqrt{7} = 0;\]
\[5 - \sqrt{34} < 0;\]
\[2\sqrt{5} = \sqrt{20} < 5\]
\[3\sqrt{2} = \sqrt{18} < 5\]
\[\sqrt{7} + \sqrt{11} \approx 2,6 + 3,3 = 5,9\]
\[В\ порядке\ возрастания:\]
\[5 - \sqrt{34};\ \ 18\sqrt{7} - 9\sqrt{28};\ \ 3\sqrt{2};\ \ 2\sqrt{5};\ \ \sqrt{7} + \sqrt{11}\text{.\ }\]