`6) 2/-3 - 1/3 . ( 4x - 5 ) = ( - 12 )/-8`
`⇔ ( - 2 )/3 - 1/3 . ( 4x - 5 ) = 3/2`
`⇔ 1/3 . ( 4x - 5 ) = ( - 2 )/3 - 3/2`
`⇔ 1/3 . ( 4x - 5 ) = ( - 13 )/6`
`⇔ 4x - 5 = ( - 13 )/6 : 1/3`
`⇔ 4x - 5 = ( - 13 )/2`
`⇔ 4x = ( - 13 )/2 + 5`
`⇔ 4x = ( - 3 )/2`
`⇔ x = ( - 3 )/2 : 4`
`⇔ x = ( - 3 )/8`
Vậy , `x = ( - 3 )/8 .`
`7) 2 . | 2/4 . x - 1/3 | - 3/2 = 5/20`
`⇔ 2 . | 1/2 . x - 1/3 | = 5/20 + 3/2`
`⇔ 2 . | 1/2 . x - 1/3 | = 7/4`
`⇔ | 1/2 . x - 1/3 | = 7/4 : 2`
`⇔ | 1/2 . x - 1/3 | = 7/8`
Trường hợp `1 : 1/2 . x - 1/3 = 7/8`
`⇔ 1/2 . x = 7/8 + 1/3`
`⇔ 1/2 . x = 29/24`
`⇔ x = 29/24 : 1/2`
`⇔ x = 29/12`
Trường hợp `2 : 1/2 . x - 1/3 = ( - 7 )/8`
`⇔ 1/2 . x = ( - 7 )/8 + 1/3`
`⇔ 1/2 . x = ( - 13 )/24`
`⇔ x = ( - 13 )/24 : 1/2`
`⇔ x = ( - 13 )/12`
Vậy , `x ∈ { 29/12 ; ( - 13 )/12 }`
`8) 3 1/8 - 9 . | 6x - 6/18 | = 25/8`
`⇔ 25/8 - 9 . | 6x - 1/3 | = 25/8`
`⇔ 9 . | 6x - 1/3 | = 25/8 - 25/8`
`⇔ 9 . | 6x - 1/3 | = 0`
`⇔ | 6x - 1/3 | = 0 : 9`
`⇔ | 6x - 1/3 | = 0`
`⇔ 6x - 1/3 = 0`
`⇔ 6x = 0 + 1/3`
`⇔ 6x = 1/3`
`⇔ x = 1/3 : 6`
`⇔ x = 1/18`
Vậy , `x = 1/18 .`
