Tìm x biết: x+4/2000+(x+3/2001)=x+2/2002+(x+1/2003)

`#Dark`

`(x+4)/2000+(x+3)/2001=(x+2)/2002+(x+1)/2003`

`⇔((x+4)/2000+1)+((x+3)/2001+1)=((x+2)/2002+1)+((x+1)/2003+1)`

`⇔(x+2004)/2000+(x+2004)/2001-(x+2004)/2002-(x+2004)/2003=0`

`⇔(x+2004)(1/2000+1/2001+1/2002+1/2003)=0`

Vì `(1/2000+1/2001+1/2002+1/2003) > 0`

`⇔x+2004=0`

`⇔x=-2004`

Vậy `S={-2004}`