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

Toán Lớp 8: Lưu avatar x^2(y^2-4)^2-6x(y^2-4)+9

Toán Lớp 8: Lưu
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x^2(y^2-4)^2-6x(y^2-4)+9

Comments ( 2 )

  1. x^2(y^2-4)^2-6x(y^2-4)+9
    Đặt y^2-4=a
    Ta có:
    x^2.a^2-6x.a+9
    =(xa)^2-2.xa.3+3^2
    =(xa-3)^2
    Thay lại:
    [x(y^2-4)-3)]^2
    =(xy^2-4x-3)^2

  2. $ x^{2} ( y^{2} – 4 )^{2} – 6x ( y^{2} – 4 ) + 9 $
    $ = [ x ( y^{2} – 4 ) ]^{2} – 2 . x ( y^{2} – 4 ) . 3 + 3^{2} $
    $ = [ x ( y^{2} – 4 ) – 3 ]^{2}$
    $ = ( xy^{2} – 4x -3  )^{2}$
             Áp dụng hằng đẳng thức số 2 
        $ (  A – B )^{2} = A^{2} – 2AB + B^{2} $

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