Question

Rút gọn: \(\sqrt{13+30\sqrt{2+\sqrt{9+4\sqrt{2}}}}\)

Answer 1

\(=\sqrt{13+30\sqrt{2+2\sqrt{2}+1}}\)

\(=\sqrt{13+30\left(\sqrt{2}+1\right)}=\sqrt{43+30\sqrt{2}}\)

\(=\sqrt{43+2\cdot\sqrt{450}}\)

\(=\sqrt{25+2\cdot5\cdot3\sqrt{2}+18}\)

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