Bài 2:
1.
`x/5 = 3/-5`
`=> x = 3/-5 . 5`
`=> x= 15/-5`
`=> x= -3`
Vậy `x= -3`
2.
`4/5 x - 8/5 + 1/2 = 0`
`=> 4/5 x - 11/10 = 0`
`=> 4/5 x = 11/10`
`=> x= 11/10 : 4/5`
`=> x = 11/10 . 5/4`
`=> x= 11/8`
Vậy `x= 11/8`
3.
`1/5 |x| = 2/5 + 1 2/5`
`=> 1/5 | x| = 2/5 + 7/5`
`=> 1/5 |x| = 9/5`
`=> |x| = 9/5 : 1/5`
`=> |x| = 9/5 . 5`
`=> |x| = 9`
`=>` \(\left[ \begin{array}{l}x=9\\x=-9\end{array} \right.\)
Vậy `x = -9` hoặc `x = 9`