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

Toán Lớp 8: Giúp mình bài này với (X^2+y^2-5)^2-4(x^2y^2-4xy+4)

Toán Lớp 8: Giúp mình bài này với
(X^2+y^2-5)^2-4(x^2y^2-4xy+4)

Comments ( 2 )

  1.       (x^2+y^2-5)^2-4(x^2y^2-4xy+4)
    = (x^2+y^2-5)^2-4(xy-2)^2
    =(x^2+y^2-5)^2- (2xy-4)^2
    =(x^2+y^2-5-2xy+4)(x^2+y^2-5+2xy-4)
    =[ (x-y)^2-1] [ (x+y)^2-9]
    =(x-y-1)(x-y+1)(x+y+3)(x+y-3)

  2. (x^2+y^2-5)^2-4(x^2y^2-4xy+4)
    =(x^2+y^2-5)^2-(4x^2y^2-16xy+16)
    =(x^2+y^2-5)^2-[(2xy)^2-2.2xy.4+4^2]
    =(x^2+y^2-5)^2-(2xy-4)^2
    =[(x^2+y^2-5)-(2xy-4)][(x^2+y^2-5)+(2xy-4)]
    =(x^2+y^2-5-2xy+4)(x^2+y^2-5+2xy-4)
    =[(x^2-2xy+y^2)+(-5+4)][(x^2+2xy+y^2)+(-5-4)]
    =[(x-y)^2-1][(x+y)^2-9]
    =[(x-y)^2-1^2][(x+y)^2-3^2]
    =(x-y-1)(x-y+1)(x+y-3)(x+y+3)
    $\text{@ThanhTruc2008}$

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

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