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

Toán Lớp 8: a, 15x ³ -5x ² +10x

Toán Lớp 8: a, 15x ³ -5x ² +10x b,28x ² -21xy ² +14x ²y c,9x ²-4 d,8-27x ³y mũ 6 e,25x ∧4 – 10x ²y+y ²

Comments ( 2 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
       $\text{a) 15x³ – 5x² + 10x}$
    $\text{= 5x .( 3x² – x + 2 )}$
       $\text{b) 28x² – 21xy² + 14x²y}$
    $\text{= 7x .(4x – 3y² + 2xy)}$
       $\text{c) 9x² – 4 = (3x – 2)(3x + 2)}$
    $\text{HĐT : A² – B² = (A – B)(A + B)}$
       $\text{d) 8 – 27x³$y^{6}$ }$
    $\text{= 2³ – (3xy²)³ = (2 – 3xy²)(4 + 6xy² + $9x²y^{4}$) }$
    $\text{HĐT: A³ – B³ = (A – B) ( A² + AB + B²)}$
       $\text{e) $25x^{4}$ – 10x²y + y²}$
    $\text{= (5x²)² – 2.5x².y + y² = (5x² – y)²}$
    $\text{HĐT: ( A – B)² = A² – 2AB + B²}$

  2. #Sad
    a)
    15x^3-5x^2+10x
    = 5x(3x^2-x+2)
    b)
    28x^2-21xy^2+14x^2y
    = 7x(4x-3y^2+2xy)
    c)
    9x^2-4
    = (3x-2)(3x+2)
    d)
    8-27x^3y^6
    = 2^3-(3xy^2)^3
    = (2-3xy^2)(4+6xy^2+9x^2y^4)
    e)
    25x^4-10x^2y+y^2
    = (5x^2)^2-2. 5x^2. y+y^2
    = (5x^2-y)^2
     

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