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

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

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

Comments ( 2 )

  1. ~ Bạn tham khảo ~
    (x-1)^3+3(x+1)^2=(x^2-2x+4)(x+2)
    <=> x^3 – 3x^2 + 3x – 1 + 3(x^2 + 2x + 1) = x^3 + 8
    <=> x^3 – 3x^2 + 3x – 1 + 3x^2 + 6x + 3 – x^3 – 8 = 0
    <=> 9x – 6 = 0
    <=> 9x = 6
    <=> x = 2/3
    Vậy x={2/3}

  2. Giải đáp + Lời giải và giải thích chi tiết:
    (x-1)³+3(x+1)²=(x²-2x+4)(x+2)
    ⇔x³-3x²+3x-1+3(x²+2x+1)= x³+8
    ⇔x³-3x²+3x-1+3x²+6x+3-x³-8=0
    ⇔ 9x -6=0
    ⇔ 9x=6
    ⇔ x=6/9
    ⇔ x=2/3
    Vậy x=2/3

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

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