`a)-2,5+|3x+5|=-1,5`
`=>|3x+5|=-1,5+2,5`
`=>|3x+5|=1`
`=>[(3x+5=1),(3x+5=-1):}`
`=>[(3x=-4),(3x=-6):}`
`=>`$\left[\begin{matrix} x=\dfrac{-4}{3} \\ x=-2 \end{matrix}\right.$
Vậy `x\in{-4/3;-2}`
`b)1/5-|1/5-x|=1/5`
`=>|1/5-x|=1/5-1/5`
`=>|1/5-x|=0`
`=>1/5-x=0`
`=>x=1/5`
Vậy `x=1/5`
`c)-5/6-|2-x|=1/3`
`=>|2-x|=-5/6-1/3`
`=>|2-x|=-7/6`
`=>`$\left[\begin{matrix} 2-x=\dfrac{-7}{6} \\ x-2=\dfrac{-7}{6}\end{matrix}\right.$
`=>`$\left[\begin{matrix} x=\dfrac{19}{6} \\ x=\dfrac{5}{6}\end{matrix}\right.$
Vậy `x\in{19/6;5/6}`
`d)|5-3x|+2/3=1/6`
`=>|5-3x|=1/6-2/3`
`=>|5-3x|=-1/2`(Vô lý)
Vậy ptrình vô nghiệm
`e)|x-2/5|-3/4=-1/2`
`=>|x-2/5|=-1/2+3/4`
`=>|x-2/5|=1/4`
`=>`$\left[\begin{matrix} x-\dfrac{2}{5}=\dfrac{1}{4} \\ \dfrac{2}{5}-x=\dfrac{1}{4}\end{matrix}\right.$
`=>`$\left[\begin{matrix} x=\dfrac{13}{20}\\x=\dfrac{3}{20}\end{matrix}\right.$
Vậy `x\in{13/20;3/20}`
`f)(1,25-4/5x)^3=-125`
`=>(1,25-4/5x)^3=(-5)^3`
`=>1,25-4/3x=-5`
`=>4/3x=1,25-(-5)`
`=>4/3x=25/4`
`=>x=25/4:4/3`
`=>x=25/3`
Vậy `x=25/3`