Đề bài

Tìm x, biết:

a)$x:{\left( {\frac{{ - 1}}{2}} \right)^3} =  - \frac{1}{2};$                b)$x.{\left( {\frac{3}{5}} \right)^7} = {\left( {\frac{3}{5}} \right)^9};$

c)${\left( {\frac{{ - 2}}{3}} \right)^{11}}:x = {\left( {\frac{{ - 2}}{3}} \right)^9};$          d)$x.{\left( {0,25} \right)^6} = {\left( {\frac{1}{4}} \right)^8}$