Giải thích các bước giải:
\[\begin{array}{l}
b,\\
{\left( { - 2} \right)^3}.{\left( {\frac{1}{2}} \right)^2} + \left( {1,75 - 25\% } \right):\frac{3}{{{{\left( { - 2} \right)}^4}}}\\
= - \frac{{{2^3}}}{{{2^2}}} + \left( {1,75 - 0,25} \right):\frac{3}{{{2^4}}}\\
= - 2 + 1,5.\frac{{{2^4}}}{3}\\
= - 2 + \frac{3}{2}.\frac{{{2^4}}}{3} = - 2 + {2^3} = - 2 + 8 = 6\\
b,\\
- \frac{1}{{30}} - \left( {\frac{4}{5} - \frac{3}{4}\sqrt x } \right) = - \frac{1}{3}\\
\Leftrightarrow \frac{4}{5} - \frac{3}{4}\sqrt x = - \frac{1}{{30}} - \left( { - \frac{1}{3}} \right)\\
\Leftrightarrow \frac{4}{5} - \frac{3}{4}\sqrt x = \frac{3}{{10}}\\
\Leftrightarrow \frac{3}{4}\sqrt x = \frac{4}{5} - \frac{3}{{10}}\\
\Leftrightarrow \frac{3}{4}\sqrt x = \frac{1}{2}\\
\Leftrightarrow \sqrt x = \frac{2}{3}\\
\Leftrightarrow x = \frac{4}{9}\\
c,\\
\frac{{x - 3}}{5} = \frac{{5 - 2x}}{{ - 11}}\\
\Leftrightarrow \frac{{2x - 6}}{{10}} = \frac{{5 - 2x}}{{ - 11}} = \frac{{\left( {2x - 6} \right) + \left( {5 - 2x} \right)}}{{10 - 11}} = \frac{{ - 1}}{{ - 1}} = 1\\
\Rightarrow \frac{{5 - 2x}}{{ - 11}} = 1 \Rightarrow x = 8
\end{array}\]
