Toán (4x+1) (12x-1) (3x+2) (x+1) – 4 giúp mình vs ạk 06/07/2021 By Katherine (4x+1) (12x-1) (3x+2) (x+1) – 4 giúp mình vs ạk
`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)` Trả lời
`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)`