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

Toán Lớp 8: (x+3)^3-x(3x+1)^2+(2x+1)(4x^2-2x+1)-3x^2=54

Toán Lớp 8: (x+3)^3-x(3x+1)^2+(2x+1)(4x^2-2x+1)-3x^2=54

Comments ( 2 )

  1. (x + 3)^3 – x(3x +1)^2 + (2x + 1)(4x^2 – 2x + 1) – 3x^2 = 54
    x^3 + 9x^2 +27x + 27 – x(9x^2 + 6x + 1) + 8x^3 + 1 – 3x^2 = 54
    x^3 + 9x^2 + 27x + 27 – 9x^3 – 6x^2 – x + 8x^3 + 1 – 3x^2 = 54
    26x + 28 = 54
    26x = 26
    x = 1
    Chúc Bạn Học Tốt

  2. #laviken#
    (x+3)^3-x(3x+1)^2+(2x+1).(4x^2-2x+1)-3x^2=54
    $\Rightarrow$ 9x^3+9x^2 +27x+27-x(9x^2+6x+1)+8x^3+1-3x^2=54
    $\Rightarrow$ 9x^3+6x^2+27x-9x^3-6x^2-x=54-27-1
    $\Rightarrow$ 26x-x=54-27-1
    $\Rightarrow$ 26x=54-27-1=26
    $\Rightarrow$ x=26/26
    $\Rightarrow$ x=1

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