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

Toán Lớp 8: Phân tích đa thức thành nhân tử a) 7x + 56×2 + 28xy

Toán Lớp 8: Phân tích đa thức thành nhân tử a) 7x + 56×2 + 28xy
b) 27 – 8×3
c) x2 – 10x + 25 – z2
d) 3x – 3y – x2 + 2xy – y

Comments ( 2 )

  1. y10000
    a )
    7x + 56x² + 28xy
    = 7x . ( 1 + 8x + 4y )
    b )
    27 – 8x³
    = ( 3 – 2x ) . ( 9 + 6x + 4x² )
    c )
    x² – 10x + 25 – z²
    = ( x² – 10x + 25 ) – z²
    = ( x – 5 )² – z²
    = ( x – 5 – z ) . ( x – 5 + z )
    d ) 
    3x – 3y – x² + 2xy – y²
    = 3 . ( x – y ) – ( x² – 2xy + y² )
    = 3 . ( x – y ) – ( x – y )²
    = 3 . ( x – y ) – ( x – y ) . ( x – y )
    = ( 3 – x + y ) . ( x – y )
     

  2. a) 7x+56x^2+28xy
    =7x(1+8x+4y)
    * Đặt nhân tử chung
    b) 27-8x^3
    =3^3-(2x)^3
    =(3-2x)(9+6x+4x^2)
    * a^3-b^3=(a-b)(a^2+ab+b^2)
    c) x^2-10x+25-z^2
    =(x^2-10x+25)-z^2
    =(x-5)^2-z^2
    =(x-5-z)(x-5+z)
    * Nhóm hạng tử
    * (a-b)^2=a^2-2ab+b^2
    * a^2-b^2=(a-b)(a+b)
    d) 3x-3y-x^2+2xy-y^2
    =(3x-3y)-(x^2-2xy+y^2)
    =3(x-y)-(x-y)^2
    =(x-y)(3-x+y)
    * Nhóm hạng tử
    * Đặt nhân tử chung
    * (a-b)^2=a^2-2ab+b^2
    * a^2-b^2=(a-b)(a+b)

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

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