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

Toán Lớp 8: câu hỏi : a) x²-25z² b) x²+4xy+4y² c) x³-2x²y+xy² d)x²+3x-4

Toán Lớp 8: câu hỏi :
a) x²-25z²
b) x²+4xy+4y²
c) x³-2x²y+xy²
d)x²+3x-4

Comments ( 2 )

  1. a) x²-25z²
    = x² – (5z)²
    = (x-5z)(x+5z)
    b) x²+4xy+4y²
    = x² + 2.x.2y+(2y)²
    = (x+2y)²
    c) x³-2x²y+xy²
    = x(x² – 2xy + y²)
    = x(x-y)²
    d)x²+3x-4
    = x² + 4x – x – 4
    = (x-1)(x+4)
     

  2. a, x^2 – 25z^2
    = x^2 – (5z)^2
    = ( x +5z)(x -5z)
    b, x^2 + 4xy + 4y^2
    = x^2 + 2. x. 2y + (2y)^2
    = ( x+2y)^2
    c, x^3 – 2x^2 y + xy^2
    = x(x^2 – 2xy + y^2 )
    =x(x -y)^2
    d, x^2 + 3x -4
    = x^2 -x + 4x -4
    = x(x-1) + 4(x-1)
    =(x-1)(x+4)
     

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

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