\(\sqrt{17-12\sqrt{2}}+\sqrt{8}=\sqrt{\left(3-2\sqrt{2}\right)^2}+2\sqrt{2}=3-2\sqrt{2}+2\sqrt{2}=3\)
\(\sqrt{7+4\sqrt{21-12\sqrt{3}}}=\sqrt{7+4\sqrt{\left(2\sqrt{3}-3\right)^2}}=\sqrt{7+4\left(2\sqrt{3}-3\right)}\)
\(=\sqrt{8\sqrt{3}-5}\) (câu này đề bài bị nhầm dấu, phải là \(\sqrt{7-4\sqrt{21-12\sqrt{3}}}\) mới hợp lý)
\(\sqrt{\sqrt{5}-\sqrt{3-\sqrt{29-12\sqrt{5}}}}=\sqrt{\sqrt{5}-\sqrt{3-\sqrt{\left(2\sqrt{5}-3\right)^2}}}\)
\(=\sqrt{\sqrt{5}-\sqrt{3-\left(2\sqrt{5}-3\right)}}=\sqrt{\sqrt{5}-\sqrt{6-2\sqrt{5}}}\)
\(=\sqrt{\sqrt{5}-\sqrt{\left(\sqrt{5}-1\right)^2}}=\sqrt{\sqrt{5}-\sqrt{5}+1}=1\)