Đáp án:
n) \(x = \dfrac{6}{{11}}\)
Giải thích các bước giải:
\(\begin{array}{l}
e)\dfrac{{15}}{2}x:\left( {9 - \dfrac{{139}}{{21}}} \right) = \dfrac{{63}}{{25}}\\
\to \dfrac{{15}}{2}x:\dfrac{{50}}{{21}} = \dfrac{{63}}{{25}}\\
\to \dfrac{{15}}{2}x = \dfrac{{63}}{{25}}.\dfrac{{50}}{{21}}\\
\to \dfrac{{15}}{2}x = 6\\
\to x = \dfrac{4}{5}\\
h)\left[ \begin{array}{l}
3x - 1 = 0\\
- \dfrac{1}{2}x + 5 = 0
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = \dfrac{1}{3}\\
x = 10
\end{array} \right.\\
i){\left( {2x + \dfrac{3}{5}} \right)^2} = \dfrac{9}{{25}}\\
\to \left| {2x + \dfrac{3}{5}} \right| = \dfrac{3}{5}\\
\to \left[ \begin{array}{l}
2x + \dfrac{3}{5} = \dfrac{3}{5}\\
2x + \dfrac{3}{5} = - \dfrac{3}{5}
\end{array} \right.\\
\to \left[ \begin{array}{l}
2x = 0\\
2x = - \dfrac{6}{5}
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 0\\
x = - \dfrac{3}{5}
\end{array} \right.\\
k)3{\left( {3x - \dfrac{1}{2}} \right)^3} = \dfrac{1}{9}\\
\to {\left( {3x - \dfrac{1}{2}} \right)^3} = - \dfrac{1}{{27}}\\
\to 3x - \dfrac{1}{2} = - \dfrac{1}{3}\\
\to 3x = \dfrac{1}{6}\\
\to x = \dfrac{1}{{18}}\\
m)\dfrac{3}{5}x + \dfrac{2}{3}x = \dfrac{1}{3}.\dfrac{{19}}{3}\\
\to \dfrac{{19}}{{15}}x = \dfrac{{19}}{9}\\
\to x = \dfrac{5}{3}\\
n)\dfrac{1}{3}x + \dfrac{2}{5}x - \dfrac{2}{5} = 0\\
\to \dfrac{{11}}{{15}}x = \dfrac{2}{5}\\
\to x = \dfrac{6}{{11}}
\end{array}\)
