Question

Rút gọn: \(\sqrt{57-14\sqrt{8}}\) - \(\sqrt{8}\)

Answer 1

\(\sqrt{57-14\sqrt{8}}-\sqrt{8}=\sqrt{49-2\cdot7\cdot\sqrt{8}+8}-\sqrt{8}=\sqrt{\left(7-\sqrt{8}\right)^2}-\sqrt{8}=7-\sqrt{8}-\sqrt{8}=7-2\sqrt{8}\)

Answer 2

\(=\sqrt{49-2.7.\sqrt{8}+8}-\sqrt{8}=7-\sqrt{8}-\sqrt{8}=7-2\sqrt{8}=7-4\sqrt{2}\)