giúp ạ

`a(1 2/3 - x) . 0,75 - 2 = 1/2`

`=> (5/3 - x) . 3/4 = 1/2 + 2`

`=> (5/3 - x) . 3/4 = 5/2`

`=> 5/3 - x = 5/2 : 3/4`

`=> 5/3 - x = 10/3`

`=> x = 5/3 - 10/3`

`=> x = -5/3`

Vậy `x = -5/3`

`b) 1 - (2x + 1/2)^2 = 3/4`

`=> (2x + 1/2)^2 = 1 - 3/4`

`=> (2x + 1/2)^2 = 1/4`

`TH1 :`

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

`=> 2x + 1/2 = 1/2`

`=> 2x = 1/2 - 1/2`

`=> 2x = 0`

`=> x = 0`

`TH2 :`

`=> (2x + 1/2)^2 = (-1/2)^2`

`=> 2x + 1/2 = -1/2`

`=> 2x = -1/2 - 1/2`

`=> 2x = -1`

`=> x = -1 : 2`

`=> x = -1/2`

Vậy `x = {0; 1/2}`