1-1/2+1/3-…-1/1990=1/996+1/997+…+1/1990 Giúp mk nha mn :))) 29/08/2021 Bởi Kennedy 1-1/2+1/3-…-1/1990=1/996+1/997+…+1/1990 Giúp mk nha mn :)))
`1-1/2 + 1/3 -…+1/1889-1/1990` `=( 1+1/3 + 1/5+…+ 1/1889) – (1/2 + 1/4 +1/6+…+1/1990)` `= (1+1/2 + 1/3+…+1/1889 + 1/1990)- 2(1/2 + 1/4 + 1/6+…+1/1990)` `= (1+1/2 + 1/3+…+1/1889 + 1/1990) – ( 1 + 1/2 + 1/3 +…+1/995)` `= 1 + 1/2+1/3+..+1/1889 + 1/1990 – 1 -1/2 -1/3 -…-1/995` `= 1/996 + 1/997 +…+ 1/1990` Bình luận
Đáp án:
NGỒI NGHĨ MÃI MỚI RA!
CHO TUÔI CTLHN NHÁ!
`1-1/2 + 1/3 -…+1/1889-1/1990`
`=( 1+1/3 + 1/5+…+ 1/1889) – (1/2 + 1/4 +1/6+…+1/1990)`
`= (1+1/2 + 1/3+…+1/1889 + 1/1990)- 2(1/2 + 1/4 + 1/6+…+1/1990)`
`= (1+1/2 + 1/3+…+1/1889 + 1/1990) – ( 1 + 1/2 + 1/3 +…+1/995)`
`= 1 + 1/2+1/3+..+1/1889 + 1/1990 – 1 -1/2 -1/3 -…-1/995`
`= 1/996 + 1/997 +…+ 1/1990`