a)
[tex] \sqrt{10816} = \sqrt{104^2} = 104[/tex]
b)
[tex] \sqrt{12 \sqrt{21505+ \sqrt{10816} } } = \sqrt{ \sqrt{12^2} \sqrt{21505+104} }= \\
= \sqrt{ \sqrt{12^2*(21505+104)} } = \sqrt{ \sqrt{12^2 *21609} } = \\
= \sqrt[4]{144*21609} = \sqrt[4]{3111696}= 42 [/tex]