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

Toán Lớp 8: Thực hiện phép tính : 3 6x ___ – ________ x- 3 x^2 – 9

Toán Lớp 8: Thực hiện phép tính :
3 6x
___ – ________
x- 3 x^2 – 9

Comments ( 2 )

  1. 3/(x – 3) – (6x)/(x^2 – 9)
    = 3/(x – 3) + (-6x)/((x – 3)(x + 3))
    = (3 . (x + 3))/((x – 3)(x + 3)) + (-6x)/((x – 3)(x + 3))
    = (3(x + 3) – 6x)/((x – 3)(x + 3))
    = (3x + 9 – 6x)/((x – 3)(x + 3))
    = (-3x + 9)/((x – 3)(x + 3))
    = (-3(x – 3))/((x – 3)(x + 3))
    = -3/(x + 3)

  2. 3/(x-3) – (6x)/(x^2-9)
    =3/(x-3) – (6x)/[(x-3)(x+3)]
    =[3.(x+3)-6x]/[(x-3)(x+3)]
    =(3x+9-6x)/[(x-3)(x+3)]
    =(-3x+9)/[(x-3)(x+3)]
    =[-3.(x-3)]/[(x-3)(x+3)]
    =(-3)/(x+3)

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