mọi người giúp mình với ạ

`a) (4x - 1)/(3 + 2x)`

ĐKXĐ : `3 + 2x \ne 0`

`<=> 2x \ne -3`

`<=> x \ne -3/2`

`b) (9 - x^2)/(x^2 - 16)`

ĐKXĐ : `x^2 - 16 \ne 0`

`<=> (x -4)(x + 4) \ne 0`

`<=> {(x - 4 \ne 0),(x + 4 \ne 0):}`

`<=> {(x \ne 4),(x \ne -4):}`

`c) (4x- 3)/(x^2- 5x)`

ĐKXĐ : `x^2 - 5x \ne 0`

`<=> x(x - 5) \ne 0`

`<=> {(x \ne 0),(x - 5 \ne 0):}`

`<=> {(x \ne 0),(x \ne 5):}`

`e) (2x - 5)/((x-1)(x+3))`

ĐKXĐ : `(x - 1)(x + 3) \ne 0`

`<=> {(x - 1 \ne 0),(x + 3 \ne 0):}`

`<=> {(x \ne 1),(x \ne -3):}`

`f) (x + 7)/(x^2 + x - 12)`

ĐKXĐ : `x^2 + x - 12 \ne 0`

`<=> x^2 + 4x- 3x - 12 \ne 0`

`<=> x(x + 4) - 3(x + 4) \ne 0`

`<=> (x + 4)(x - 3) \ne 0`

`<=> {(x + 4 \ne 0),(x - 3 \ne 0):}`

`<=> {(x \ne -4),(x \ne 3):}`