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

Toán Lớp 8: A. (x+1)³ – (x²-2)(x+3)+4x B. (6x⁴y – 9x³y² + 12x²y³) : 3x²y

Toán Lớp 8: A. (x+1)³ – (x²-2)(x+3)+4x
B. (6x⁴y – 9x³y² + 12x²y³) : 3x²y

Comments ( 2 )

  1. $#Dứa$
    $\text{a, (x+1)³ – (x²-2)(x+3)+4x}$
    $\text{= x³ + 3x² + 3x + 1 – ( x³ + 3x² – 2x – 6) + 4x}$
    $\text{= x³ + 3x² + 3x +1 – x³ – 3x² + 2x + 6 + 4x}$
    $\text{= (x³ – x³) + (3x² – 3x²) + (3x + 2x + 4x) +(1 + 6)}$
    $\text{= 9x + 7}$
    $\text{b, (6x⁴y – 9x³y² + 12x²y³) : 3x²y}$
    $\text{ = (6x⁴y : 3x²y) +(-9x³y² : 3x²y) +(12x²y³ : 3x²y)}$
    $\text{= 2x² – 3xy + 4y²}$
     

  2. Giải đáp:
     
       (x+1)³ – (x²-2)(x+3)+4x
    = x³ + 3x² + 3x +1 – ( x³ +3x² – 2x -6) + 4x
    = x³ + 3x² + 3x +1 – x³ – 3x² + 2x + 6 + 4x
    = (x³-x³) + (3x²-3x²) +(3x + 2x + 4x) +(1+6)
    =    9x +7
    B.   (6x⁴y – 9x³y² + 12x²y³ )  : 3x²y
    = (6x⁴y  : 3x²y) +(-9x³y² : 3x²y) +(12x²y³ : 3x²y)
    = 2x² – 3xy + 4y²

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