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

Toán Lớp 8: Phân tích đa thức thành nhân tử: a) xy.(x+y)-2x-27 b) xy.(x-y)-2x+2y c) y(x+y)-x-y d) 2y(x-y)^2+x(y-x)^2

Toán Lớp 8: Phân tích đa thức thành nhân tử:
a) xy.(x+y)-2x-27
b) xy.(x-y)-2x+2y
c) y(x+y)-x-y
d) 2y(x-y)^2+x(y-x)^2

Comments ( 2 )

  1. ~rai~
    \(a)xy(x+y)-2x-2y\\=xy(x+y)-(2x+2y)\\=xy(x+y)-2(x+y)\\=(x+y)(xy-2).\\b)xy(x-y)-2x+2y\\=xy(x-y)-(2x-2y)\\=xy(x-y)-2(x-y)\\=(x-y)(xy-2).\\c)y(x+y)-x-y\\=y(x+y)-(x+y)\\=(x+y)(y-1).\\d)2y(x-y)^2+x(y-x)^2\\=2y(x-y)^2+x(x-y)^2\\=(x-y)^2(2y+x).\)

  2.  a) 
    xy( x + y) – 2x – 2y
    = xy( x + y) – 2( x + y)
    = (xy – 2)( x + y)
    b)
    xy( x – y) – 2x + 2y
    = xy( x – y) – 2( x – y)
    = (xy – 2)( x – y)
    c)
    y(x+y)-x-y
    = y( x + y) – ( x + y)
    = ( x + y)( y – 1)
    d)
    2y(x – y)^2 + x ( y – x)^2 (1)
    Do  x – y và y – x là hai số đối nhau nên bình phương lên sẽ bằng nhau
    ⇒ ( x – y)^2 = ( y – x)^2
    (1) ⇔ 2y( x – y)^2 + x( x – y)^2
    = ( x – y)^2( 2y + x)

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