\(\sqrt{11-4\sqrt{7}}-\sqrt{2}\sqrt{8+3\sqrt{7}}\)
\(=\sqrt{7-2\sqrt{4}\sqrt{7}+4}-\sqrt{16+6\sqrt{7}}\)
\(=\sqrt{\left(\sqrt{7}-\sqrt{4}\right)^2}-\sqrt{9+2\sqrt{9}\sqrt{7}+7}\)
\(=\sqrt{7}-\sqrt{4}-\sqrt{9}-\sqrt{7}\)
\(=-2-3=-5\)
chúc bn hc giỏi
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Ta có: \(\sqrt{11-4\sqrt{7}}-\sqrt{2}\sqrt{8+3\sqrt{7}}=\sqrt{11-4\sqrt{7}}-\sqrt{16+6\sqrt{7}}\)
\(=\sqrt{\left(\sqrt{7}-2\right)^2}-\sqrt{\left(3-\sqrt{7}\right)^2}\)
\(=\left|\sqrt{7}-2\right|-\left|3-\sqrt{7}\right|\)
\(=\sqrt{7}-2-3+\sqrt{7}\)
\(=2\sqrt{7}-5\)
