X+1/2019+x+2/2018=x+3/2017+x+4/2016 Giúp mk vs nha mk cảm ơn trc ạ

`(x+1)/2019+(x+2)/2018=(x+3)/2017+(x+4)/2016`

`<=>((x+1)/2019+1)+((x+2)/2018+1)=((x+3)/2017+1)+((x+4)/2016+1)`

`<=>(x+2020)/2019+(x+2020)/2018=(x+2020)/2017+(x+2020)/2016`

`<=>(x+2020)/2019+(x+2020)/2018-(x+2020)/2017-(x+2020)/2016=0`

`<=>(x+2020)(1/2019+1/2018-1/2017-1/2016)=0`

Nhận thấy:

`1/2019<1/2017=>1/2020-1/2017<0`

`1/2018<1/2016=>1/2018-1/2016<0`

`=>1/2019+1/2018-1/2017-1/2016<0`

`=>x+2020=0`

`<=>x=-2020`

Vậy `S={-2020}`