Question

Rut gon :

B= \(\sqrt{\sqrt{5}-\sqrt{3}-\sqrt{29}-12\sqrt{5}}\)

Answer 1

phải đề ghi dầy o nha : \(\sqrt{\sqrt{5-\sqrt{3}}-\sqrt{29-12\sqrt{5}}}\)

sai thôi

Answer 2

Sửa đề: Rút gọn: \(B=\sqrt{\sqrt{5}-\sqrt{3-\sqrt{29-12\sqrt{5}}}}\)

Giải: Ta có:

\(B=\sqrt{\sqrt{5}-\sqrt{3-\sqrt{29-12\sqrt{5}}}}\)

\(=\sqrt{\sqrt{5}-\sqrt{3-\sqrt{\left(2\sqrt{5}-3\right)^2}}}\)

\(=\sqrt{\sqrt{5}-\sqrt{3-2\sqrt{5}+3}}\)

\(=\sqrt{\sqrt{5}-\sqrt{6-2\sqrt{5}}}\)

\(=\sqrt{\sqrt{5}-\sqrt{\left(\sqrt{5}-1\right)^2}}\)

\(=\sqrt{\sqrt{5}-\sqrt{5}+1}=\sqrt{1}=1\)

Vậy \(B=1\)

Answer 3

\(12\sqrt{5}=\sqrt{720}\)

vì \(\sqrt{720}>\sqrt{29}>\sqrt{5}>\sqrt{3}\)

nên \(\sqrt{5}-\sqrt{3}-\sqrt{29}-12\sqrt{5}< 0\)

\(\Rightarrow\) đề sai