giúp mik với

$\displaystyle  \begin{array}{{>{\displaystyle}l}}
7/\ \frac{31}{36} -\left(\frac{1}{3} -x\right)^{2} =\frac{5}{6}\\
\Leftrightarrow \left(\frac{1}{3} -x\right)^{2} =\frac{1}{36}\\
\Leftrightarrow \left[ \begin{array}{l l}
\frac{1}{3} -x=\frac{1}{6}\\
\frac{1}{3} -x=\frac{-1}{6}
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l l}
x=\frac{1}{6}\\
x=\frac{1}{2}
\end{array} \right.\\
Vậy\ nghiệm\ của\ pt\ là\ x=\frac{1}{6} \ và\ x=\frac{1}{2}\\
8/\ \frac{3}{4} -|x-\frac{3}{2} |=\frac{1}{6}\\
\Leftrightarrow |x-\frac{3}{2} |=\frac{7}{12}\\
\Leftrightarrow \left[ \begin{array}{l l}
x-\frac{3}{2} =\frac{7}{12}\\
x-\frac{3}{2} =\frac{-7}{12}
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l l}
x=\frac{25}{12}\\
x=\frac{11}{12}
\end{array} \right.\\
Vậy\ nghiệm\ của\ pt\ là\ x=\frac{25}{12} \ và\ x=\frac{11}{12}\\
9/\ \frac{2}{3} |2x+\frac{1}{2} |=5\\
\Leftrightarrow |2x+\frac{1}{2} |=\frac{15}{2}\\
\Leftrightarrow \left[ \begin{array}{l l}
2x+\frac{1}{2} =\frac{15}{2}\\
2x+\frac{1}{2} =\frac{-15}{2}
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l l}
2x=7\\
2x=-8
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l l}
x=\frac{7}{2}\\
x=-4
\end{array} \right.\\
Vậy\ nghiệm\ của\ pt\ là\ x=\frac{7}{2} \ và\ x=-4
\end{array}$