a)
[tex] \sqrt{25} + \sqrt[3]{27} + \sqrt[4]{81} = \\ \\ 5 + \sqrt[3]{ {3}^{3} } + \sqrt[4]{ {3}^{4} } = \\ \\ 5 + 3 + 3 = \\ \\ 11[/tex]
b)
[tex] \sqrt{64} + \sqrt[3]{ - 64} + \sqrt[6]{64} = \\ \\ 8 + \sqrt[3]{ { ( - 1)(2)}^{6} } + \sqrt[6]{ {2}^{6} } = \\ \\ 8 + {2}^{2} \times \sqrt[3]{ - 1} + 2 = \\ 8 + 4 + ( - 1) + 2 = \\ \\ 13[/tex]
