Tính: A = 1/ 2020 + 2/ 2020 + 3/ 2020 + .... + 2018 / 2020 + 2019 / 2020
Giải thích
Chọn B
A=12020+22020+32020+...+20182020+20192020A=1+2+3+...+2018+20192020A=(2019+1)×2019:12020=20192
Chọn B
A=12020+22020+32020+...+20182020+20192020A=1+2+3+...+2018+20192020A=(2019+1)×2019:12020=20192