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

Toán Lớp 8: A=(x-3)^3-(x+1)^3+12x.(x-1) rút gọn đa thức trên

Toán Lớp 8: A=(x-3)^3-(x+1)^3+12x.(x-1)
rút gọn đa thức trên

Comments ( 2 )

  1. A=(x-3)^3-(x+1)^3+12x.(x-1)
    =(x^3-9x^2+27x-27)-(x^3+3x^2+3x+1)+(12x^2-12x)
    =x^3-9x^2+27x-27-x^3-3x^2-3x-1+12x^2-12x
    =(x^3-x^3)+(-9x^2-3x^2+12x^2)+(27x-3x-12x)+(-27-1)
    =0+0+12x+(-28)
    =12x-28
    Vậy A=12x-28

  2. Giải đáp:
    A=(x-3)^3-(x+1)^3+12x.(x-1)
    A=x³ – 9x² + 27x – 27 – x³ – 3x² – 3x – 1 + 12x² – 12x
    A= ( x³ – x³) + ( -9x² – 3x² + 12x² )+( 27x – 3x – 12x)+( -27 -1)
    A= 12x – 28

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