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

Toán Lớp 8: x^2-2x-y^2+4y-3=? làm giúp em với

Toán Lớp 8: x^2-2x-y^2+4y-3=? làm giúp em với

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết:
    x^2 – 2x – y^2 + 4y – 3
    = x^2 – 2x – y^2 + 4y – 4 + 1
    = x^2 – 2x + 1 – y^2 + 4y – 4
    = (x^2 – 2x + 1) – (y^2 – 4y + 4)
    = (x – 1)^2 – (y – 2)^2
    = (x – 1 + y – 2)[x – 1 – (y – 2)]
    = (x + y – 3)(x – 1 – y + 2)
    = (x + y – 3)(x – y – 1)

  2. x^2 – 2x – y^2 + 4y – 3
    = x^2 – 2x – y^2 + 4y +1 – 4
    = ( x^2 – 2x + 1 ) – ( y^2 + 4 – 4y )
    = ( x – 1 )^2 – ( y^2 + 2^2 – 2.2.y )
    = ( x – 1 )^2 – ( y – 2 )^2  
    = [ x – 1 – ( y – 2 ) ] . [ x – 1 + ( y – 2 ) ]
    = ( x – 1 – y + 2 ) ( x – 1 + y – 2 )
    = ( x – y – 1  )( x + y – 3 )  
     

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