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

Toán Lớp 8: (x-2)^3-4(x+2)(x-2)+3(x-2)(x^2+2x+4) Đề bài:rút gọn biểu thức

Toán Lớp 8: (x-2)^3-4(x+2)(x-2)+3(x-2)(x^2+2x+4)
Đề bài:rút gọn biểu thức

Comments ( 2 )

  1. #tnvt
    (x-2)^3-4(x+2)(x-2)+3(x-2)(x^2+2x+4)
    =x^3-3.x^2 .2+3.x.2^2 -2^3-4(x^2-2^2)+3(x^3-2^3)
    =x^3-6x^2+12x-8-4x^2+16+3x^3-24
    =4x^3-10x^2+12x-16

  2. Lời giải:
    \(\begin{array}{l}(x-2)^3-4(x+2)(x-2)+3(x-2)(x^2+2x+4)\\=x^3-6x^2+12x-8-4(x^2-4)+3(x^3-8)\\=3x^3-24+x^3-6x^2+12x-8-4x^2+16\\=4x^3-10x^2+12x-16\end{array}\)

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