Đáp án:
\[x = \dfrac{{91}}{{16}}\]
Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
\dfrac{2}{5} - \dfrac{3}{5}.\left( {x - 2} \right) = {\left( {\dfrac{{ - 1}}{2}} \right)^3} - {\left( {\dfrac{3}{4}} \right)^3}.{\left( { - 2} \right)^2}\\
\Leftrightarrow \dfrac{2}{5} - \dfrac{3}{5}.\left( {x - 2} \right) = \dfrac{{ - 1}}{8} - {\left( {\dfrac{3}{4}} \right)^3}.4\\
\Leftrightarrow \dfrac{2}{5} - \dfrac{3}{5}.\left( {x - 2} \right) = - \dfrac{1}{8} - \dfrac{{{3^3}}}{{{4^2}}}\\
\Leftrightarrow \dfrac{2}{5} - \dfrac{3}{5}\left( {x - 2} \right) = - \dfrac{1}{8} - \dfrac{{27}}{{16}}\\
\Leftrightarrow \dfrac{2}{5} - \dfrac{3}{5}\left( {x - 2} \right) = - \dfrac{{29}}{{16}}\\
\Leftrightarrow \dfrac{3}{5}.\left( {x - 2} \right) = \dfrac{2}{5} - \left( { - \dfrac{{29}}{{16}}} \right)\\
\Leftrightarrow \dfrac{3}{5}\left( {x - 2} \right) = \dfrac{{177}}{{80}}\\
\Leftrightarrow x - 2 = \dfrac{{177}}{{80}}:\dfrac{3}{5}\\
\Leftrightarrow x - 2 = \dfrac{{59}}{{16}}\\
\Leftrightarrow x = \dfrac{{59}}{{16}} + 2\\
\Leftrightarrow x = \dfrac{{91}}{{16}}
\end{array}\)
Vậy \(x = \dfrac{{91}}{{16}}\)
