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

Toán Lớp 8: rút gọn B= (x-1)^3 -(x+1)^3 +6(x+1) (x-1)

Toán Lớp 8: rút gọn B= (x-1)^3 -(x+1)^3 +6(x+1) (x-1)

Comments ( 2 )

  1. B = (x-1)^3 – (x+1)^3+6(x+1)(x-1)
    = x^3 – 3x^2 +3x – 1 – x^3 – 3x^2-3x-1+6x^2 – 6
    = ( x^3-x^3)+(-3x^2-3x^2+6x^2)+(3x-3x)+(-1-1-6)
    =-8

  2. Giải đáp:
    B=-8
    Lời giải và giải thích chi tiết:
    B=(x-1)³-(x+1)³+6(x+1)(x-1)
        =x³-3x²+3x-1-(x³+3x²+3x+1)+6(x²-1)
        =x³-3x²+3x-1-x³-3x²-3x-1+6x²-6
        =(x³-x³)+(-3x²-3x+6x²)+(3x-3x)+(-1-1-6)
        =-8

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