Tính 1/1.3 +1/3.5 +1/5.7 +……. +1/2009.2011 20/07/2021 Bởi Peyton Tính 1/1.3 +1/3.5 +1/5.7 +……. +1/2009.2011
`1/1.3 +1/3.5 +1/5.7 +……. +1/2009.2011` ` = 1/2 . (2/1.3 +2/3.5 +2/5.7 +……. +2/2009.2011)` ` = 1/2 . (1 – 1/3 + 1/3 – 1/5 + 1/5 – 1/7 + …. + 1/2009 – 1/2011)` ` = 1/2 . (1 – 1/2011)` ` = 1/2 . 2010/2011` ` = 1005/2011` Bình luận
Đáp án: `1005/2011` Giải thích các bước giải: `1/(1.3) +1/(3.5) +1/(5.7) +……. +1/(2009.2011)` `= 1/2 . ( 1 – 1/3 + 1/3 – 1/5 + 1/5 – 1/7 + …. + 1/2009 – 1/2011 )` `= 1/2.(1 – 1/2011)` `= 1/2 . 2010/2011` `= 1005/2011` Bình luận
`1/1.3 +1/3.5 +1/5.7 +……. +1/2009.2011`
` = 1/2 . (2/1.3 +2/3.5 +2/5.7 +……. +2/2009.2011)`
` = 1/2 . (1 – 1/3 + 1/3 – 1/5 + 1/5 – 1/7 + …. + 1/2009 – 1/2011)`
` = 1/2 . (1 – 1/2011)`
` = 1/2 . 2010/2011`
` = 1005/2011`
Đáp án:
`1005/2011`
Giải thích các bước giải:
`1/(1.3) +1/(3.5) +1/(5.7) +……. +1/(2009.2011)`
`= 1/2 . ( 1 – 1/3 + 1/3 – 1/5 + 1/5 – 1/7 + …. + 1/2009 – 1/2011 )`
`= 1/2.(1 – 1/2011)`
`= 1/2 . 2010/2011`
`= 1005/2011`