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

Toán Lớp 8: Tính: ( 2x – 5) . ( $x^{2}$ + 8) – $x^{2}$( 2x + 11) + 40x -8

Toán Lớp 8: Tính:
( 2x – 5) . ( $x^{2}$ + 8) – $x^{2}$( 2x + 11) + 40x -8

Comments ( 2 )

  1. text{   (2x – 5) . (x² + 8) – x²(2x + 11) + 40x – 8}
    text{= 2x(x² + 8) – 5(x² + 8) – 2x³ – 11x² + 40x – 8}
    text{= 2x³ + 16x – 5x² – 40 – 2x³ – 11x² + 40x – 8}
    text{= (2x³ – 2x³) + (16x + 40x) + (-5x² – 11x²) + (-40 – 8)}
    text{= 0 + 56x – 16x² – 48}
    text{= 56x – 16x² – 48}
     

  2. (2x-5)(x^2+8) – x^2(2x+11) + 40x – 8
    =2x^3-5x^2 +16x – 40 – 2x^3 – 11x^2 +40x – 8
    = (2x^3-2x^3) +(-5x^2-11x^2) +(16x +40x) + (-40 – 8)
    = -16x^2 + 56x – 48  

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