3x-2/ x+5 + 2x = 12

`@` Lời giải:

`(3x-2)/(x+5) + 2x = 12` `(x \ne -5)`

`=> 3x - 2 + 2x(x+5) = 12(x+5)`

`=> 3x - 2 + 2x^2 + 10x = 12x + 60`

`=> 2x^2 + 13x - 2 = 12x + 60`

`=> 2x^2 + 13x - 2 - 12x - 60 = 0`

`=> 2x^2 + x - 62 = 0`

`=> 2x^2+x=62`

`=> x^2 + 1/2x = 31`

`=> x^2 + 1/2x + 1/16 = 31+1/16`

`=> (x+1/4)^2 = 497/16`

`=> (x+1/4)^2 = (sqrt{497}/4)^2` hoặc `(x+1/4)^2=(-sqrt{497}/4)^2`

`@ x + 1/4 = sqrt{497}/4`

`=> x = sqrt{497}/4 - 1/4` (tm)

`@ x + 1/4 = -sqrt{497}/4`

`=> x = -sqrt{497}/4 - 1/4` (tm)

Vậy `x = ±sqrt{497}/4-1/4`