a, `2/3 + x = -1/12`

`x = -1/12 - 2/3`

`x = -3/4`

Vậy `x = -3/4`

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b, `5/11 x + 4 = 6 1/11`

`5/11 x + 4 = 67/11`

`5/11 x = 67/11 - 4`

`5/11 x = 23/11`

`x = 23/11 . 11/5`

`x = 23/5`

Vậy `x = 23/5`

``

c, `(2x + 1)^2 = 36/36`

`(2x + 1)^2 = 1^2`

`2x +1 = 1` hoặc `2x + 1 = -1`

`2x = 0` hoặc `2x = -2`

`x = 0` hoặc `x = -1`

Vậy `x in {0;-1}`

``

d, `(3x-1)^3 = -1/27`

`(3x-1)^3 = (-1/3)^3`

`3x - 1 = -1/3`

`3x = -1/3 + 1`

`3x = 2/3`

`x = 2/3 . 1/3`

`x = 2/9`

Vậy `x = 2/9`