bài 4
`a)`
`|2x-1|+1=4`
`=>|2x-1|=4-1`
`=>|2x-1|=3`
TH1
`2x-1=3`
`=>2x=3+1`
`=>2x=4`
`=>x=2`
TH2
`2x-1=-3`
`=>2x=-3+1`
`=>2x=-2`
`=>x=-1`
vậy `x∈{2;-1}`
`b)`
`8-|1-3x|=3`
`=>|1-3x|=8-3`
`=>|1-3x|=5`
TH1
`1-3x=5`
`=>3x=1-5`
`=>3x=-4`
`=>x=-4/3`
TH2
`1-3x=-5`
`=>3x=1-(-5)`
`=>3x=6`
`=>x=2`
vậy `x∈{-4/3;2}`
`c)`
`5x.(x-1/3)=0`
`=>` \(\left[ \begin{array}{l}5x=0\\x-\dfrac{1}{3}=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=0\\x=\dfrac{1}{3}\end{array} \right.\)
vậy `x∈{0;1/3}`
`d)`
`1/20-(x-8/5)=1/10`
`=>x-8/5=1/20-1/10`
`=>x-8/5=-1/20`
`=>x=-1/20+8/5`
`=>x=31/20`
vậy `x=31/20`
