Đáp án:
`a)` `x=3/20`
`b)` \(\left[ \begin{array}{l}x=\dfrac{1}{3}\\x=\dfrac{-5}{3}\end{array} \right.\)
Giải thích các bước giải:
`a)`
`2/5-x=1/4`
`=>x=2/5-1/4`
`=>x=3/20`
`b)`
`|x+2/3|-2/5=3/5`
`=>|x+2/3|=3/5+2/5`
`=>|x+2/3|=5/5`
`=>|x+2/3|=1`
`=>`\(\left[ \begin{array}{l}x+\dfrac{2}{3}=1\\x+\dfrac{2}{3}=-1\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=1-\dfrac{2}{3}\\x=-1-\dfrac{2}{3}\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=\dfrac{1}{3}\\x=\dfrac{-5}{3}\end{array} \right.\)
