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

Toán Lớp 8: làm tính nhân : (2x^2n+3x^2n-1)(x^1-2n-3x^2-2n)

Toán Lớp 8: làm tính nhân :
(2x^2n+3x^2n-1)(x^1-2n-3x^2-2n)

Comments ( 2 )

  1. \qquad (2x^(2n)+3x^(2n-1))(x^(1-2n)-3x^(2-2n))
    =2x^(2n).x^(1-2n)-2x^(2n).3x^(2-2n)+3x^(2n-1).x^(1-2n)-3x^(2n-1).3x^(2-2n)
    =2x^(2n+1-2n)-6x^(2n+2-2n)+3x^(2n-1+1-2n)-9x^(2n-1+2-2n)
    =2x-6x^2+3-9x
    =-6x^2-7x+3

  2. (2x^(2n)+3x^(2n-1))(x^(1-2n)-3x^(2-2n))
    = 2x^(2n) . x^(1-2n) – 2x^(2n) . 3x^(2-2n) + 3x^(2n-1) . x^(1-2n) – 3x^(2n-1) . 3x^(2-2n)
    =2x^(2n+1-2n) – 6x^(2n+2-2n) + 3x^(2n-1+1-2n) – 9x^(2n-1+2-2n)
    =2x-6x^2+3-9x
    =-6x^2-7x+3
     

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

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