Tìm x , biết: 27 ( 3 x − 1/ 5 ) ^3 = − 8.

2) \(27{\left( {\frac{1}{3}x - \frac{1}{5}} \right)^3} = - 8\)

 \({\left( {\frac{1}{3}x - \frac{1}{5}} \right)^3} = - \frac{8}{{27}}\)

 \({\left( {\frac{1}{3}x - \frac{1}{5}} \right)^3} = {\left( { - \frac{2}{3}} \right)^3}\)

 \(\frac{1}{3}x - \frac{1}{5} = - \frac{2}{3}\)

 \(\frac{1}{3}x = - \frac{2}{3} + \frac{1}{5}\)

 \(\frac{1}{3}x = \frac{{ - 10}}{{15}} + \frac{3}{{15}}\)

 \(\frac{1}{3}x = \frac{{ - 7}}{{15}}\)

 \(x = \frac{{ - 7}}{5}.\)

Vậy \(x = \frac{{ - 7}}{5}.\)