(4x+1) (12x-1) (3x+2) (x+1) – 4 giúp mình vs ạk

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1. `4x+1)(12x−1)(3x+2)(x+1)−4`

   `=[(4x+1)(3x+2)] . [(12x−1)(x+1)]−4`

   `=(12x^2+11x+2)(12x^2+11x−1)−4`

   Đặt `12x^2 + 11x -1 = a` ta được:

   `(a+3)a−4`

   `=a^2+3a−4`

   `=a^2−a+4a−4`

   `=a(a−1)+4(a−1)`

   `=(a−1)(a+4)`

   `=(12x^2+11x−1−1)(12x^2+11x−1+4)`

   `=(12x^2+11x−2)(12x^2+11x+3)`

    

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