Tìm x , biết :a) (frac{{ - ,11}}{{12}},.

* Hướng dẫn giải

a) \(\frac{{ - \,11}}{{12}}\,.\,\user2{x}\, + \,0,25\, = \,\frac{5}{6}\)           

          \(\begin{array}{l}
\frac{{ - \,11}}{{12}}\,.\,\user2{x}\, + \,\frac{1}{4}\, = \,\frac{5}{6}\\
\frac{{ - \,11}}{{12}}\,.\,\user2{x} = \frac{5}{6} - \frac{1}{4}\\
\frac{{ - \,11}}{{12}}\,.\,\user2{x} = \frac{7}{{12}}\\
x = \frac{{ - 7}}{{11}}
\end{array}\)

b) \({\left( {\user2{x} - 1} \right)^5} =  - 32\)

Ta có \({\left( {\user2{x}\, - \,1} \right)^5}\, = \,{\left( { - \,2} \right)^5}\)

\( \Rightarrow \,\,\user2{x}\, - \,1\, = \, - \,2\,\,\,\, \Rightarrow \,\,\,\,x\,\, = \,\, - \,1\)