[tex]a = 0,(4)\\\\10a = 4,(4)\\\\10a - a = 4,(4) - 0,(4)\\\\9a = 4 \ \ /:9\\\\a =\frac{4}{9}\\\\0,(4)= \frac{4}{9}\\\\\\(0,(4))^{-0,5} =(\frac{4}{9})^{-\frac{1}{2}} = (\frac{9}{4})^{\frac{1}{2}} = ((\frac{3}{2})^{2})^{\frac{1}{2}} = \frac{3}{2} = 1\frac{1}{2} = 1,5[/tex]
