Đáp án + Giải thích các bước giải:
`2xxy+(1/2+1/6+1/12+...+1/(2020xx2021))=4041/2021`
`2xxy+(1/(1xx2)+1/(2xx3)+1/(3xx4)+...+1/(2020xx2021))=4041/2021`
`2xxy+(1-1/2+1/2-1/3+1/3-1/4+...+1/2020-1/2021)=4041/2021`
`2xxy+(1-1/2021)=4041/2021`
`2xxy+(2021/2021-1/2021)=4041/2021`
`2xxy+2020/2021=4041/2021`
`2xxy=4041/2021-2020/2021`
`2xxy=1`
`y=1:2`
`y=1/2`