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`a) (3x^2 + 7x + 9) : (x-1)`

`(3x^2 + 7x + 9) = (x-1)(3x+10) + 19`

Vậy `(3x^2 + 7x + 9) : (x-1) = 3x + 10` (dư `19`)

`f) 16x^2 - 9 : (4x+3)`

`= (4x-3)(4x+3) : (4x+3)`

`= 4x-3`

`g) (5x^2 - 2x + 1)(x - 2) - 3x(x + 1) + 7`

`= (5x^3 - 10x^2 - 2x^2 + 4x + x - 2) - (3x^2 + 3x) + 7`

`= 5x^3 - 12x^2 + 5x - 2 - 3x^2 - 3x + 7`

`= 5x^3 - 15x^2 + 2x + 5`

`h) (7x^3 - 2x^2) : (-2x^2) + (5/4 x^2 - 3x) : x - 1/2 x(x-1)(2x+1)`

`= (7x^3/(-2x^2) - 2x^2/(-2x^2)) + (5/4 x^2/x - 3x/x) - 1/2 x(2x^2 + x - 2x - 1)`

`= (-7/2 x + 1) + (5/4 x - 3) - 1/2 x(2x^2 - x - 1)`

`= -7/2 x + 1 + 5/4 x - 3 - x^3 + 1/2 x^2 + 1/2 x`

`= -x^3 + 1/2 x^2 - 7/4 x - 2`