Đáp án:
`S=\{2021\}`
Giải thích các bước giải:
`(x-3)/2018+(x-2)/2019=(x-2019)/2+(x-2018)/3`
`<=>((x-3)/2018-1)+((x-2)/2019-1)=((x-2019)/2-1)+((x-2018)/3-1)`
`<=>(x-3-2018)/2018+(x-2-2019)/2019=(x-2019-2)/2+(x-2018-3)/3`
`<=>(x-2021)/2018+(x-2021)/2019=(x-2021)/2+(x-2021)/3`
`<=>(x-2021)/2018+(x-2021)/2019-(x-2021)/2-(x-2021)/3=0`
`<=>(x-2021)(1/2018+1/2019-1/2-1/3)=0`
Do `1/2018+1/2019-1/2-1/3\ne 0`
`=>x-2021=0`
`<=>x=2021`
Vậy `S=\{2021\}`
