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

Toán Lớp 8: ׳-7ײ-21×+27 bằng bao nhiêu ạ

Toán Lớp 8: ׳-7ײ-21×+27 bằng bao nhiêu ạ

Comments ( 2 )

  1. $\textit{Giải đáp + Lời giải và giải thích chi tiết:}$
    $x^3 – 7x^2 – 21x + 27$
    $= x^3 + 3^3 – (7x^2 + 21x)$
    $= (x + 3)^3 – 9x(x + 3) – 7x(x + 3)$
    $= (x + 3)^3 – (9x + 7x)(x + 3)$
    $= (x + 3)^2 . (x + 3) – 16x(x + 3)$
    $= [(x + 3)^2 – 16x](x + 3)$
    $= (x^2 + 6x + 9 – 16x)(x + 3)$
    $= (x^2 + 9 – 10x)(x + 3)$
     

  2. x^{3} – 7x^{2} – 21x + 27
    = ( x^{3} + 27) – ( 7x^{2} + 21x )
    = ( x + 3)( x^{2} – 3x + 9) – 7x( x + 3)
    = ( x + 3)( x^{2} – 3x + 9 – 7x)
    = ( x + 3)( x^{2} – 10x + 9)
    Bạn tham khảo!
     

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

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