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`a,`
`|x+6|=18`
`->` \(\left[ \begin{array}{l}x+6=18\\x+6=-18\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}x=18-6\\x=-18-6\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}x=12\\x=-24\end{array} \right.\)
Vậy `x=12` hoặc `x=-24`
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`b,`
`|2x-7|=30`
`->` \(\left[ \begin{array}{l}2x-7=30\\2x-7=-30\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}2x=30+7\\2x=-30+7\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}2x=37\\2x=-23\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}x=37:2\\x=-23:2\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}x=\dfrac{37}{2}\\x=\dfrac{-23}{2}\end{array} \right.\)
Vậy `x=37/2` hoặc `x=(-23)/2`
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`c,`
`|3y-1/2| -1=2/5`
`-> |3y-1/2|=2/5 + 1`
`-> |3y-1/2|=7/5`
`->` \(\left[ \begin{array}{l}3y-\dfrac{1}{2}=\dfrac{7}{5}\\3y-\dfrac{1}{2}=\dfrac{-7}{5}\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}3y=\dfrac{7}{5}+\dfrac{1}{2}\\3y=\dfrac{-7}{5}+\dfrac{1}{2}\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}3y=\dfrac{19}{10}\\3y=\dfrac{-9}{10}\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}y=\dfrac{19}{10}:3\\y=\dfrac{-9}{10}:3\end{array} \right.\) $\\$ `->` \(\left[ \begin{array}{l}y=\dfrac{19}{30}\\y=\dfrac{-9}{30}\end{array} \right.\)
Vậy `y=19/30` hoặc `y=(-9)/30`
