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

Toán Lớp 8: (xy+x)^2-(x+y)^2 giúp ik mn ơi

Toán Lớp 8: (xy+x)^2-(x+y)^2 giúp ik mn ơi

Comments ( 2 )

  1. (xy+x)^2-(x+y)^2
    =[(xy+x)-(x+y)][(xy+x)+(x+y)]
    =(xy+x-x-y)(xy+x+x+y)
    =(xy-y)(xy+2x+y)
    =y(x-1)(xy+2x+y)
    * a^2-b^2=(a-b)(a+b)
     

  2. (xy+x)^2-(x+y)^2
    =(xy)^2+2.xy.x+x^2-(x^2+2xy+y^2)
    =x^2y^2+2x^2y+x^2-x^2-2xy-y^2
    =x^2y^2+2x^2y+(x^2-x^2)-2xy-y^2
    =x^2y^2+2x^2y-2xy-y^2
    Phân tích:
    (xy+x)^2-(x+y)^2
    =(xy+x-x-y)(xy+x+x+y)
    =(xy-y)(xy+2x+y)
    =y(x-1)(xy+2x+y)
     

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

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