`1/(1.4)+1/(4.7)+1/(7.10)+...+1/(2020.2023)`

Đáp án:

Giải thích các bước giải:

`1/1.4+1/4.7+1/7.10+...+1/2020.2023`

`=` `3(1/1.4+1/4.7+1/7.10+...+1/2020.2023)`

`=``3(3/1.4+3/4.7+3/7.10+...+3/2020.2023)`

`=` `3((4-1)/1.4+(7-4)/4.7+(10-7)/7.10+...+(2023-2020)/2020.2023)`

`=``3(4/4.1-1/1.4+7/4.7-4/4.7+10/7.10-7/7.10+...+2023/2020.2023-2020/2020.2023)`

`=` `3(1-1/4+1/4-1/7+1/7-1/10+...+1/2020-1/2023)`

`=` `3(1-1/2023)`

`=` `3(2023/2023-1/2023)`

`=` `3.(2022/2023)`

`=` `6066/2023`