Question

rút gọn biểu thức sau: \(\sqrt{4+\sqrt{15}}-\sqrt{4-\sqrt{15}}\)

 

Answer 1

\(=\dfrac{\sqrt{8+2\sqrt{15}}-\sqrt{8-2\sqrt{15}}}{\sqrt{2}}=\dfrac{\sqrt{5}+\sqrt{3}-\sqrt{5}+\sqrt{3}}{\sqrt{2}}=\dfrac{2\sqrt{3}}{\sqrt{2}}=\sqrt{6}\)