a)
Có: \(1+2\sqrt{2}=1+\sqrt{8}< 1+\sqrt{9}=1+3=4\)
Vậy \(4>1+2\sqrt{2}\)
b) Có: \(2\sqrt{6}-1=\sqrt{24}-1< \sqrt{25}-1=5-1=4\)
Vậy \(4>2\sqrt{6}-1\)
c) Có: \(3\sqrt{3}=\sqrt{27}< \sqrt{28}=2\sqrt{7}\)
=> \(3\sqrt{3}< 2\sqrt{7}\)
=> \(-3\sqrt{3}>-2\sqrt{7}\)