`e)`
`(5-x)(x-1) + x (x+7) = 34`
`=> (5 . x - 5 . 1 - x . x + x . 1) + (x . x + x . 7) = 34`
`=> (5x - 5 - x^2 + x) + (x^2 + 7x) =34`
`=>5x - 5 - x^2 + x + x^2 + 7x=34`
`=> (x^2 - x^2) + (5x + x +7x) - 5 = 34`
`=> 13x - 5 = 34`
`=> 13x = 39`
`=> x = 3`
Vậy `x=3`
`d)`
`(4x+2)(x-3) - (2x-2)(2x+2) = -6`
`=> (4x . x - 4x . 3 + 2 . x - 2 . 3) - [ (2x)^2 - 2^2] =-6`
`=> (4x^2 - 12x + 2x - 6) - (4x^2- 4) = -6`
`=> 4x^2 -12x+2x-6-4x^2+4=-6`
`=> (4x^2 - 4x^2) + (2x - 12x) + (4-6) = -6`
`=> -10x - 2 = -6`
`=> -10x = -4`
`=> x = 2/5`
Vậy `x=2/5`
`f)`
`6x (x-1) - (3x-4)(2x-1) = 0`
`=> (6x . x - 6x . 1) - (3x . 2x - 3x . 1 - 4 . 2x + 4.1) = 0`
`=> (6x^2 - 6x) - (6x^2 - 3x -8x +4)=0`
`=> 6x^2 - 6x - 6x^2 + 3x+8x-4=0`
`=> (6x^2 - 6x^2) + (8x+3x-6x) - 4=0`
`=> 5x - 4=0`
`=>5x=4`
`=>x=4/5`
Vậy `x=4/5`
