Đáp án:
a. \(x = \frac{6}{{11}}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\frac{1}{3}x + \frac{2}{5}x - \frac{2}{5} = 0\\
\to \left( {\frac{1}{3} + \frac{2}{5}} \right)x = \frac{2}{5}\\
\to \left( {\frac{{5 + 6}}{{15}}} \right)x = \frac{2}{5}\\
\to \frac{{11}}{{15}}x = \frac{2}{5}\\
\to x = \frac{2}{5}:\frac{{11}}{{15}}\\
\to x = \frac{6}{{11}}\\
d.\frac{1}{3}\left( {2x - 5} \right) = - \frac{2}{3} - \frac{3}{2}\\
\to \frac{1}{3}\left( {2x - 5} \right) = \frac{{ - 4 - 9}}{6}\\
\to \frac{1}{3}\left( {2x - 5} \right) = - \frac{{13}}{6}\\
\to 2x - 5 = - \frac{{13}}{6}:\frac{1}{3}\\
\to 2x - 5 = - \frac{{13}}{2}\\
\to 2x = - \frac{{13}}{2} + 5 = \frac{{ - 13 + 10}}{2}\\
\to 2x = - \frac{3}{2}\\
\to x = - \frac{3}{4}\\
b.\left[ \begin{array}{l}
2x - 3 = 0\\
6 - 2x = 0
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = \frac{3}{2}\\
x = \frac{6}{2} = 3
\end{array} \right.\\
e.DK:x \ne \frac{1}{2}\\
\frac{1}{{3\left( {2x - 1} \right)}} = - 5 - \frac{1}{4} = \frac{{ - 20 - 1}}{4}\\
\to \frac{1}{{3\left( {2x - 1} \right)}} = - \frac{{21}}{4}\\
\to 3\left( {2x - 1} \right) = - \frac{4}{{21}}\\
\to 2x - 1 = - \frac{4}{{21}}:3\\
\to 2x - 1 = - \frac{4}{{63}}\\
\to 2x = \frac{{59}}{{63}}\\
\to x = \frac{{59}}{{126}}(TM)
\end{array}\)
