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

Toán Lớp 8: Phân tích các đa thức sau thành nhân tử `:` `1.` `5x^2 + 5xy – x – y` `2.` `x^2 + y^2 – z^2 – 2xy` `3.` `5x^2 – 10xy + 5y^2 – 20z^2` `4

Toán Lớp 8: Phân tích các đa thức sau thành nhân tử :
1. 5x^2 + 5xy – x – y
2. x^2 + y^2 – z^2 – 2xy
3. 5x^2 – 10xy + 5y^2 – 20z^2
4. a^3 – a + b^3 – b

Comments ( 2 )

  1. Giải đáp:
    1) ( 5x – 1 )( x + y )
    2) ( x – y – z )( x – y + z )
    3) 5 . ( x – y – 2z )( x – y + 2z )
    4) ( a + b )( a^2 + b^2 – ab – 1 )
    Lời giải và giải thích chi tiết:
    1) 5x^2 + 5xy – x – y
    = 5x . ( x + y ) – ( x + y ) . 1
    = ( 5x – 1 )( x + y )
    2) x^2 + y^2 – z^2 – 2xy
    = x^2 – 2xy + y^2 – z^2
    = ( x – y )^2 – z^2
    = ( x – y – z )( x – y + z )
    3) 5x^2 – 10xy + 5y^2 – 20z^2
    = 5 . ( x^2 – 2xy + y^2 – 4z^2 )
    = 5 . [ ( x – y )^2 – ( 2z )^2 ]
    = 5 . ( x – y – 2z )( x – y + 2z )
    4) a^3 – a + b^3 – b
    = ( a^3 + b^3 ) – ( a + b ) . 1
    = ( a + b )( a^2 – ab + b^2 ) – ( a + b ) . 1
    = ( a + b )( a^2 + b^2 – ab – 1 )

  2. Giải đáp + Lời giải và giải thích chi tiết:
    1. 5x^2 + 5xy – x – y  
    =  ( 5x^2 + 5xy ) + ( – x – y )
    =  5x ( x + y ) – ( x + y )
    =  ( x + y ) ( 5x – 1 )
    2. x^2 + y^2 – z^2 – 2xy  
    =  ( x – y )^2 – z^2  
    =  ( x – y – z ) ( x – y + z )
    3. 5x^2 – 10xy + 5y^2 – 20z^2
    =  5 ( x^2 – 2xy + y^2 – 4z^2 )
    =  ( x – y – 2z ) ( x – y + 2z )
    =  5 ( x – y – 2z ) ( x – y + 2z )  
    4. a^3 – a + b^3 – b
    =  ( a + b ) ( a^2 – ab + b^2 – 1 )
    #nocopy
    @huy

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

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