E = 1/6 + 1/12 + 1/20 +…..+ 1/2450 Question E = 1/6 + 1/12 + 1/20 +…..+ 1/2450 in progress 0 Môn Toán Eirian 5 years 2021-05-20T10:56:26+00:00 2021-05-20T10:56:26+00:00 2 Answers 37 views 0
Answers ( )
Đáp án:
`E=12/25`
Giải thích các bước giải:
`E = 1/6 + 1/12 + 1/20 +…..+ 1/2450`
`E=1/2.3+1/3.4+1/4.5+…+1/49.50`
`E=1/2-1/3+1/3-1/4+1/4-1/5+…+1/49-1/50`
`E=1/2-(1/3-1/3+1/4-1/4+1/5-…-1/49+1/50)`
`E=1/2-1/50`
`E=12/25`
`E= 1/6 + 1/12 + 1/20 +…+1/2450`
`E= 1/2.3 + 1/3.4 + 1/4.5 +….+ 1/49.50`
`E= 1/2 – 1/3 + 1/3 – 1/4+ 1/4 -1/5+…+ 1/49 – 1/50`
`E= 1/2 -(1/3 -1/3) -(1/4-1/4)-…..-(1/49-1/49) – 1/50`
`E= 1/2 – 1/50`
`E=12/25`
Vậy `E= 12/25`