`c)`
`2x^2 + 3(x-1)(x+1) = 5x (x+1)`
`=> 2x^2 + 3 (x^2 -1) = 5x^2 + 5x`
`=> 2x^2 + 3x^2 - 3 = 5x^2 +5x`
`=> 2x^2 + 3x^2 - 5x^2 - 5x = 3`
`=> -5x = 3`
`=> x = -3/5`
Vậy `x=-3/5`
`d)`
`(8-5x)(x+2) + 4 (x-2)(x+1) + (x-2)(x+2)`
`= (8x +16 - 5x^2- 10x) + (4x - 8)(x+1) + (x^2 - 2^2)`
`= 8x + 16 - 5x^2 - 10x + 4x^2+ 4x - 8x - 8 + x^2 - 4`
` = 4 -6x`
`e)`
`4(x-1)(x+5) - (x+2)(x+5) = 3 (x-1)(x+2)`
`=> (4x-4)(x+5) - (x+2)(x+5) = (3x-3)(x+2)`
`=> 4x^2 + 20x - 4x - 20 - x^2 - 5x - 2x - 10 = 3x^2 + 6x - 3x- 6`
`=> 3x^2 + 9x - 30 = 3x^2 + 3x - 6`
`=> 3x^2 + 9x - 30 - 3x^2- 3x+6=0`
`=> 6x -24=0`
`=> 6x=24`
`=>x=4`
Vậy `x=4`
`f)`
`(3x-1)(2x+7) - (x+1)(6x-5) =16`
`=> (6x^2 + 21x- 2x-7) - (6x^2 -5x +6x - 5) =16`
`=> 6x^2 + 21x - 2x - 7 - 6x^2 + 5x - 6x + 5 =16`
`=> 18x - 2 =16`
`=> 18x =18`
`=> x=1`
Vậy `x=1`
