Cho A=1/1.2+1/3.4+1/5.6+...+1/2015.2016 và B=1/1008+2/1009+1/1010+...+1/2016. Tính B-A
Những câu hỏi liên quan
cho A=1/1.2+1/3.4+1/5.6+.....+1/2015.2016 và B= 1/1008+1/1009+....+1/2016
tính A-B
CMR 1/1.2+1/3.4+1/5.6+...+1/2015.2016=1/1009+1/1010+...+1/2016
B = 1/1.2 + 1/3.4 +..+1/2015.2016
B = 1-1/2 + 1/3 - 1/4 +...+ 1/2015 - 1/2016
B = 1+ 1/2 + 1/3 +..+1/2015 + 1/2016 - 2( 1/2 + 1/4 + ..1/2016)
B = 1/1009 + 1/1010 +.. + 1/2016 ( dpcm)
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chứng minh 1/1.2+1/3.4+1/5.6+...+1/2015.2016=1/1009+1/1010+...+1/2016
cho A=1/1.2+1/3.4+1/5.6+....+1/2021.2022 và B=1011+1010/1012+1009/1013+1008/1014+...+2/2020+1/2021 Chứng minh rằng : B/A là số nguyên
Chứng minh: \(\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+...+\frac{1}{2015.2016}=\frac{1}{1009}+\frac{1}{1010}+...+\frac{1}{2016}\).
CM:
1/1.2 + 1/3.4 + 1/5.6 + ...+ 1/2015.2016 = 1/1009 + 1/1010 + ... + 1/2016
CMR: 1/1.2+1/3.4+1/5.6+1/7.8+...+1/2013.2014=1/1008+1/1009+1/1010+...+1/2013+1/2014
Chứng minh rằng
1/1.2 + 1/3.4 + 1/5.6 + 1/7.8 + ... + 1/2013.2014 = 1/1008 + 1/1009 + 1/1010 +...+ 1/2013+ 1/2014
$2015=5.13.31$2015=5.13.31
Ta có: $1.2.....1007=1.2...5....13.....31...1007\text{ chia hết cho }5.13.31=2015$1.2.....1007=1.2...5....13.....31...1007 chia hết cho 5.13.31=2015
$1008.1009.....2004=1008....\left(1010\right)....\left(1014\right)...\left(1023\right)....2004$1008.1009.....2004=1008....(1010)....(1014)...(1023)....2004
$=1008....\left(5.202\right)....\left(13.78\right)....\left(31.33\right)...2004\text{ chia hết cho }5.13.33=2015$=1008....(5.202)....(13.78)....(31.33)...2004 chia hết cho 5.13.33=2015
Do đó tổng 2 số trên chia hết cho 2015.
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(1/1008 + 1/1009 + 1/1010 +...+ 1/2014) : [1/2 + 1/(3.4) +1/(5.6) +...+ 1/(2013.2014)]=???