2 câu trả lời
`1/(1xx2) + 1/(2xx3) + 1/(3xx4) + ... + 1/(2021 xx 2022)`
`= 1/1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ... + 1/2021 - 1/2022`
`= 1/1 - 1/2022`
`= 2021/2022`
Vậy `1/(1xx2) + 1/(2xx3) + 1/(3xx4) + ... + 1/(2021 xx 2022) = 2021/2022`
`#dtkc`