2: Ta có: \(\sqrt{14-8\sqrt{3}}\)
\(=\sqrt{8-2\cdot\sqrt{8}\cdot\sqrt{6}+6}\)
\(=\sqrt{\left(2\sqrt{3}-\sqrt{6}\right)^2}\)
\(=\left|2\sqrt{3}-\sqrt{6}\right|\)
\(=2\sqrt{3}-\sqrt{6}\)
6: Ta có: \(\sqrt{13+4\sqrt{10}}\)
\(=\sqrt{8+2\cdot\sqrt{8}\cdot\sqrt{5}+5}\)
\(=\sqrt{\left(2\sqrt{2}+\sqrt{5}\right)^2}\)
\(=\left|2\sqrt{2}+\sqrt{5}\right|\)
\(=2\sqrt{2}+\sqrt{5}\)
7: Ta có: \(\sqrt{35-12\sqrt{6}}\)
\(=\sqrt{27-2\cdot\sqrt{27}\cdot\sqrt{8}+8}\)
\(=\sqrt{\left(3\sqrt{3}-2\sqrt{2}\right)^2}\)
\(=\left|3\sqrt{3}-2\sqrt{2}\right|\)
\(=3\sqrt{3}-2\sqrt{2}\)
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