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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: Phân tích đa thức thành nhân tử `(x^2 + 2x)(x^2 +4x+3)-24`

Toán Lớp 8: Phân tích đa thức thành nhân tử
(x^2 + 2x)(x^2 +4x+3)-24

Comments ( 2 )

  1. (x^2 + 2x)(x^2 + 4x + 3) – 24
    = (x^2 + 2x)( x^2 + 3x + x + 3) – 24
    = (x^2 + 2x)[ x(x + 3) + (x + 3)] – 24
    = x(x + 2)(x + 1)(x + 3) – 24
    = [ x(x + 3)][ (x + 2)(x + 1)] – 24
    = (x^2 + 3x)(x^2 + x + 2x + 2) – 24
    = (x^2 + 3x)(x^2 + 3x + 2) – 24
    Đặt a = x^2 + 3x
    => a(a + 2) – 24
    = a^2 + 2a – 24
    = a^2 + 6a – 4a – 24
    = a(a + 6) – 4(a + 6)
    = (a – 4)(a + 6)
    => (x^2 + 3x – 4)(x^2 + 3x + 6)
     

  2. x2+2x)(x2+4x+3)−24
    =(x2+2x)(x2+3x+x+3)−24
    =x(x+2)(x+1)(x+3)−24
    =[x(x+3)][(x+2)(x+1)]−24
    =(x2+3x)(x2+x+2x+2)−24
    =(x2+3x)(x2+3x+2)−24
    Cho  a=x2+3x
    ⇒a(a+2)−24
    =a2+2a−24
    =a2+6a−4a−24
    =(a−4)(a+6)
    ⇒(x2+3x−4)
    ❤❤❤

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222-9+11+12:2*14+14 = ? ( )

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