7) 1/x+2 – 1/x-2 = 3x-12/x^2-4 8) 2/x-1 + 1/x+1 = 2x-1/x^2-1

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1. $#DYHUN$

   `1/(x+2)-1/(x-2)=(3x-12)/(x²-4) (1)`

   `ĐKXĐ:x`$\neq$`±2`

   `(1)⇔(x-2)/((x-2)(x+2))-(x+2)/((x-2)(x+2))=(3x-12)/((x-2)(x+2))`

   `⇒x-2-x-2=3x-12`

   `⇔x-x-3x=2+2-12`

   `⇔-3x=-8`

   `⇔x=8/3`

   Vậy`S={8/3}`

   …………………………………………. 

   `2/(x-1)+1/(x+1)=(2x-1)/(x²-1) (1)`

   `ĐKXĐ:x`$\neq$`±1`

   `(1)⇔(2(x+1))/((x-1)(x+1))+(x-1)/((x-1)(x+1))=(2x-1)/((x-1)(x+1))`

   `⇒2x+2+x-1=2x-1`

   `⇔2x-2x+x=1-1-2`

   `⇔x=-2`

   Vậy `S={2}`

    

    

    

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