[tex]x=[(-\frac{3}{4})^{3}*(-\frac{3}{4})^{5}]:[(-\frac{3}{4})^{3}]^{2}=\\ \\ =(-\frac{3}{4})^{8}:(-\frac{3}{4})^{6}=(-\frac{3}{4})^{2}=\frac{9}{16}.\\ \\ \\ ->(2x-\frac{1}{2x})=2*\frac{9}{16}-\frac{1}{2*\frac{9}{16}}=\frac{9}{8}-\frac{1}{\frac{9}{8}}=\frac{9}{8}-\frac{8}{9}=\frac{81-64}{72}=\frac{17}{72}.[/tex]
/rfd
