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

Toán Lớp 8: Tính: $\text{( x – 1 )( x – 2 )( 3x – 4 )}$

Toán Lớp 8: Tính:
$\text{( x – 1 )( x – 2 )( 3x – 4 )}$

Comments ( 2 )

  1. (x – 1)(x – 2)(3x – 4)
    = [x.x – 1.x – 2.x + (-1)(-2)](3x – 4)
    = (x^2 – x – 2x + 2)(3x – 4)
    = (x^2 – 3x + 2)(3x – 4)
    = 3x . x^2 – 3x.3x + 2.3x – 4x^2 + (-4)(-3x) + (-4).2
    = 3x^3 – 9x^2 + 6x – 4x^2 + 12x – 8
    = 3x^3 – 13x^2 + 18x – 8
     
     

  2. (x-1)(x-2)(3x-4)
    =[x.(x-2)-(x-2)].(3x-4)
    =(x^2-2x-x+2).(3x-4)
    =(x^2-3x+2)(3x-4)
    =x^2.(3x-4)-3x.(3x-4)+2.(3x-4)
    =3x^3-4x^2-9x^2+12x+6x-8
    =3x^3-13x^2+18x-8

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