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

Toán Lớp 8: thu gọn đa thức C=(x-y)²-(x+y)² A=xy(x²+xy-3y²) B=(x+2).(3x²-4x)

Toán Lớp 8: thu gọn đa thức
C=(x-y)²-(x+y)²
A=xy(x²+xy-3y²)
B=(x+2).(3x²-4x)

Comments ( 2 )

  1. $ C = ( x – y )^2 – ( x + y ) ^2 $
        $= ( x – y + x + y ) ( x – y – x – y ) $
        $= 2x . ( -2y ) $
        $= – 4xy $
    $ A = xy ( x^2 + xy – 3y^2 )$
        $ = x^3y + x^2y^2 – 3xy^3 $
    $ B = ( x + 2 ) ( 3x^2 – 4x ) $
        $= 3x^3 + 6x^2 – 4x^2 – 8x $
        $= 3x^3 + 2x^2 – 8x $
     

  2. C=(x-y)^2-(x+y)^2
    =(x-y-x-y)(x-y+x+y)
    =(-2y).2x
    =-4xy
    A=xy(x²+xy-3y²)
    =x^3y+x^2y^2-3xy^3
    B=(x+2).(3x²-4x)
    =x.(3x^2-4x)+2.(3x^2-4x)
    =3x^3-4x^2+6x^2-8x
    Cho mk xin hay nhất please
    Thank you

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

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