( x - 3 ) (x + 3) < (x + 2) +3 giải giúp e với ạ

`(x - 3)(x +3) < (x + 2) + 3`

`<=> x^2 - 9 < x + 2 + 3`

`<=> x^2 - 9  - x - 5 < 0`

`<=> x^2 - x - 14 < 0`

`<=> x^2 - x +1/4 -(57)/4 < 0`

`<=> (x -1/2)^2 - (57)/4 < 0` 

`<=> (x - 1/2 - (\sqrt{57})/2)(x-1/2 + (\sqrt{57})/2) < 0`

`<=> (x - (1 + \sqrt{57})/2)(x - (1 - \sqrt{57})/2) < 0`

`@ {(x - (1 + \sqrt{57})/2 > 0),(x - (1 - \sqrt{57})/2 < 0):}`

`<=> {(x > (1 + \sqrt57})/2),(x < (1 - \sqrt{57})/2):}`

`<=> {(1 + \sqrt{57})/2 < x < (1 - \sqrt{57})/2` (vô lí)

`@ {(x - (1 + \sqrt{57})/2 < 0),(x - (1- \sqrt{57})/2 > 0):}`

`<=> {(x < (1 + \sqrt{57})/2),(x > (1 - \sqrt{57})/2):}`

`<=> (1- \sqrt{57})/2 < x < (1 + \sqrt{57})/2` (tm)

Vậy `S = {x \in R|(1 - \sqrt{57})/2 < x < (1 + \sqrt{57})/2}`

`@`Duongg7109612009