`|2/3x-2/5|-1/2=1-(-2/3)|`
`|2/3x-2/5|-1/2=5/3`
`|2/3x-2/5|=13/6`
`[(2/3x-2/5=13/6),(2/3x-2/5=-13/6):}`
`[(x=77/20),(x=-53/20):}`
\(\left|\dfrac{2}{3}x-\dfrac{2}{5}\right|-\dfrac{1}{2}=1-\left(-\dfrac{2}{3}\right)\)
\(\Leftrightarrow\left|\dfrac{2}{3}x-\dfrac{2}{5}\right|-\dfrac{1}{2}=\dfrac{5}{3}\Leftrightarrow\left|\dfrac{2}{3}x-\dfrac{2}{5}\right|=\dfrac{13}{6}\)
TH1 : \(\dfrac{2}{3}x-\dfrac{2}{5}=\dfrac{13}{6}\Leftrightarrow\dfrac{2}{3}x=\dfrac{77}{30}\Leftrightarrow x=\dfrac{77}{20}\)
TH2 : \(\dfrac{2}{3}x-\dfrac{2}{5}=-\dfrac{13}{6}\Leftrightarrow\dfrac{2}{3}x=-\dfrac{53}{30}\Leftrightarrow x=-\dfrac{53}{20}\)
b) Ta có: \(\left|\dfrac{2}{3}x-\dfrac{2}{5}\right|-\dfrac{1}{2}=1-\left(-\dfrac{2}{3}\right)\)
\(\Leftrightarrow\left|\dfrac{2}{3}x-\dfrac{2}{5}\right|=1+\dfrac{2}{3}+\dfrac{1}{2}\)
\(\Leftrightarrow\left|\dfrac{2}{3}x-\dfrac{2}{5}\right|=\dfrac{13}{6}\)
\(\Leftrightarrow\left[{}\begin{matrix}\dfrac{2}{3}x-\dfrac{2}{5}=\dfrac{-13}{6}\\\dfrac{2}{3}x-\dfrac{2}{5}=\dfrac{13}{6}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}\dfrac{2}{3}x=\dfrac{-53}{30}\\\dfrac{2}{3}x=\dfrac{77}{30}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-53}{20}\\x=\dfrac{77}{20}\end{matrix}\right.\)