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

Toán Lớp 8: x^3+3x^2-x-3,(2x-3)^2-9(x-1)^2

Toán Lớp 8: x^3+3x^2-x-3,(2x-3)^2-9(x-1)^2

Comments ( 2 )

  1. Giải đáp:
    Đúng hông ta ?? :))
     
    Lời giải và giải thích chi tiết:
    1) x^3 + 3x^2 – x – 3
    = ( x^3 + 3x^2 ) – ( x + 3 )
    = x^2 . ( x + 3 ) – ( x + 3 )
    = ( x^2 – 1 ) . ( x + 3 )
    = ( x – 1 ) . ( x + 1 ) . ( x + 3 )
    2) ( 2x – 3 )^2 – 9 . ( x – 1 )^2
    = ( 2x – 3 )^2 – 3^2 . ( x – 1 )^2
    = (2x – 3 )^2 – [ 3 . ( x + 1 )]^2
    = (2x – 3 )^2 – ( 3x + 3 )^2
    = [(2x – 3 ) – ( 3x + 3 )] . [(2x – 3 ) + ( 3x + 3 )]
    = ( 2x – 3x – 3 – 3 ) . ( 2x + 3x – 3 + 3 )
    = ( -5x – 6 ) . 5x

  2. x^3+3x^2-x-3
    =(x^3+3x^2)-(x+3)
    =x^2(x+3)-(x+3)
    =(x+3)(x^2-1)
    =(x+3)(x+1)(x-1)
    (2x-3)^2-9(x-1)^2
    =[(2x-3)-9(x-1)].[(2x-3)+9(x-1)]
    =(2x-3-9x+9)(2x-3+9x+1)
    =(-7x+6)(11x-2)

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