Tính P=x^10-10x^9+10x^8 -10x^7+…+10x^2+10x+2 với x=9

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P=x^10-10x^9+10x^8 -10x^7+…+10x^2+10x+2 với x=9

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Quinn 2 năm 2021-08-22T14:47:23+00:00 2 Answers 9 views 0

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  1. hoaianh
    0
    2021-08-22T14:48:28+00:00
    Reply

    Đáp án:

     

    Giải thích các bước giải:

     `x=9`

    `=>10=x+1` thay vào P

    `=>P=x^10-x^9(x+1)+x^8(x+1)-x^7(x+1)+…..+x^2(x+1)+x(x+1)+2`

    `=x^10-x^10-x^9+x^9+x^8-x^8-x^7+…….+x^3+x^2+x^2+x+2`

    `=2x^2+x+2`

    `=162+9+2`

    `=173`

  2. mocmien
    0
    2021-08-22T14:48:53+00:00
    Reply

    `x=9`

    `⇒x+1=10`

    `P=x^10-10x^9+10x^8-10x^7+…+10x^2+10x+2`

    `P=x^10-(x+1)x^9+(x+1)^8-(x+1)x^7+…+(x+1)x^2+(x+1)x+2`

    `P=x^10-x^10-x^9+x^9+x^8-x^8-x^7+…+x^3+x^2+x^2+x+2`

    `P=2x^2+x+2`

    `P=2.9^2+9+2`

    `P=173`

     

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