Question

\(\sqrt{5}+\sqrt{9-4\sqrt{5}}\)

Answer 1

\(=\sqrt{5}+\sqrt{5-2.2.\sqrt{5}+4}=\sqrt{5}+\sqrt{\left(\sqrt{5}-2\right)^2}=\sqrt{5}+\sqrt{5}-2=2\sqrt{5}-2\)

Answer 2

Ta có : \(\sqrt{5}+\sqrt{9-4\sqrt{5}}=\sqrt{5}+\sqrt{9-2\sqrt{20}}=\sqrt{5}+\sqrt{\left(\sqrt{5}-2\right)^2}=\sqrt{5}+\sqrt{5}-2=2\sqrt{5}-2\)Chúc bạn học tốt!!!