\(\sqrt{5-2\sqrt{6}}-\sqrt{5+2\sqrt{6}}\\ =\sqrt{\left(\sqrt{3}-\sqrt{2}\right)^2}-\sqrt{\left(\sqrt{3}+\sqrt{2}\right)^2}\\ =\left|\sqrt{3}-\sqrt{2}\right|-\left|\sqrt{3}+\sqrt{2}\right|\\ =\sqrt{3}-\sqrt{2}-\sqrt{3}-\sqrt{2}\\ =-2\sqrt{2}\)
c: Ta có: \(\sqrt{5-2\sqrt{6}}-\sqrt{5+2\sqrt{6}}\)
\(=\sqrt{3}-\sqrt{2}-\sqrt{3}-\sqrt{2}\)
\(=-2\sqrt{2}\)