Question

C/M : Đẳng Thức \(\sqrt{9+4\sqrt{5}}\)  - \(\sqrt{5}\)   = 2

Answer 1

\(TC:\)

\(\sqrt{9+4\sqrt{5}}-\sqrt{5}=\sqrt{\left(\sqrt{5}\right)^2+4\sqrt{2}+2^2}-\sqrt{5}\)

\(=\sqrt{\left(\sqrt{5}+2\right)^2}-\sqrt{5}\)

\(=\sqrt{5}+2-\sqrt{5}\)

\(=2\left(dpcm\right)\)