`1,`

`(x-2).(2x-3) + 2x^2 - 5x = 3`

`<=> 2x^2 - 4x - 3x + 6 + 2x^2 - 5x = 3`

`<=> 4x^2 - 7x - 5x + 6 - 3 = 0`

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

`<=> x = (3 +√6)/2` hoặc `x = (3 - √6)/2`

`2,`

`(3x-2).(x+7) - 3x.(x-2) = 5`

`<=> 3x^2 + 21x - 2x - 14 - 3x^2 + 6 = 5`

`<=> 19x - 8 - 5 = 0`

`<=> 19x - 13 = 0`

`<=> x = 13/19`

`3,`

`(x+6).(x-2) - x.(x-3) = 6`

`<=> x^2 + 6x - 2x - 12 - x^2 + 3x = 6`

`<=> 7x - 12 - 6 = 0`

`<=> 7x - 18 = 0`

`<=> x = 18/7`

#Yoshimoto Shizuka