Đáp án:

Giải thích các bước giải:

Bài `8` : 

`a)`

` - 5 1/2x + 1 = 3/4 - 7/6 `

` - 11/2x + 1 = 9/12 - 14/12 `

` - 11/2x + 1 = - 5/12 `

` - 11/2x = - 5/12 - 1 `

` - 11/2x = - 5/12 - 12/12 `

` - 11/2x = - 17/12 `

` x = ( - 17/12 ) : ( - 11/2 ) `

` x = 17/66`

Vậy `x = 17/66`

`--------------`

`b)`

` 2x - 2/3 - 7x = 3/2 - 1 `

` ( 2x - 7x ) - 2/3 = 3/2 - 2/2 `

` ( 2 - 7 )x - 2/3 = 1/2 `

` - 5x = 1/2 + 2/3 `

` - 5x = 3/6 + 4/6 `

` - 5x = 7/6 `

` x = 7/6 : ( - 5 ) `

` x = - 7/30 `

Vậy `x = - 7/30 `

`--------------`

`c)`

` 3/2x - 2/5 = 1/3x - 1/4 `

` 3/2x - 1/3x = - 1/4 + 2/5 `

` ( 3/2 - 1/3 )x = - 5/20 + 8/20 `

` ( 9/6 - 2/6 )x = 3/20 `

` 7/6x = 3/20 `

` x = 3/20 : 7/6 `

` x = 9/70 `

Vậy `x = 9/70`