a. [tex] (\frac{w^{-5}}{w^{-9} })^{ \frac{1}{2} } \\ ( \frac{w^{9} }{w^{5} })^{ \frac{1}{2} } \\ (w^{9-5})^{ \frac{1}{2} } \\ (w^{4})^{ \frac{1}{2} } \\ \sqrt{w^{4} } \\ w^{2} [/tex]
b.[tex](m^{6})^{ \frac{-2}{3} } \\ (\frac{1}{m^{6} })^{\frac{2}{3} } \\ \frac{ \sqrt[3]{1^{2} } }{ \sqrt[3]{m^{6} }^{2} } \\ \frac{ \sqrt[3]{1} }{m^{2*2} } \\ \frac{1}{m^{4} } [/tex]
Hope this helps!