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![](https://rs.olm.vn/images/avt/0.png?1311)
\(x\)là dấu nhân hả bạn? Nếu vậy thì mk làm cho nhé
\(A=\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot....\cdot\left(1-\frac{1}{20}\right)\)
\(A=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot.......\cdot\frac{17}{18}\cdot\frac{18}{19}\cdot\frac{19}{20}=\frac{1}{20}\)
Vậy \(A=\frac{1}{20}\)
\(B=1\frac{1}{2}\cdot1\frac{1}{3}\cdot1\frac{1}{4}\cdot........\cdot1\frac{1}{2005}\cdot1\frac{1}{2006}\cdot1\frac{1}{2007}\)
\(B=\frac{3}{2}\cdot\frac{4}{3}\cdot\frac{5}{4}\cdot......\cdot\frac{2006}{2005}\cdot\frac{2007}{2006}\cdot\frac{2008}{2007}=\frac{2008}{2}=1004\)
Vậy \(B=1004\)
DẤU CHẤM LÀ DẤU NHÂN
a,
\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}....\frac{19}{20}=\frac{1}{20}\)
b, \(1\frac{1}{2}.1\frac{1}{3}....1\frac{1}{2017}=\frac{3}{2}.\frac{4}{3}....\frac{2018}{2017}=\frac{2018}{2}=1009\)
![](https://rs.olm.vn/images/avt/0.png?1311)
A/ \(\left(10\frac{3}{4}+3\frac{4}{5}\right)-\left(5\frac{3}{4}-1\frac{1}{5}\right)\)
\(=\left(10\frac{3}{4}-5\frac{3}{4}\right)+\left(3\frac{4}{5}+1\frac{1}{5}\right)\)
\(=5+5\)
\(=10\)
chúc bạn học tốt nha
![](https://rs.olm.vn/images/avt/0.png?1311)
a. 2006/2005 x 2007/2006 x 2008/2007 x 2009/2008 x 2010/2009'
= 2006 x 2007 x 2008 x 2009 x 2010 / 2005 x 2006 x 2007 x 2008 x 2009
= 2010/2005
= 402/401
\(\left(1+\frac{1}{2005}\right)x\left(1+\frac{1}{2006}\right)x\left(1+\frac{1}{2007}\right)x\left(1+\frac{1}{2008}\right)x\left(1+\frac{1}{2009}\right)\)
\(=\frac{2006}{2005}x\frac{2007}{2006}x\frac{2008}{2007}x\frac{2009}{2008}x\frac{2010}{2009}\)
\(=\frac{2010}{2005}\)
\(=\frac{402}{401}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\frac{1}{2}x\frac{2}{3}x\frac{3}{4}x...x\frac{2006}{2007}=\frac{1}{2007}\)
k nha bạn
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot...\cdot\left(1-\frac{1}{2003}\right)\cdot\left(1-\frac{1}{2004}\right)\)
\(A=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot...\cdot\frac{2002}{2003}\cdot\frac{2003}{2004}\)
\(A=\frac{1\cdot2\cdot3\cdot...\cdot2002\cdot2003}{2\cdot3\cdot4\cdot...\cdot2003\cdot2004}\)
\(A=\frac{1}{2004}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:
\(B=\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)........\left(1-\frac{1}{2017}\right).\left(1-\frac{1}{2018}\right)\)
\(\Rightarrow B=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.......\frac{2016}{2017}.\frac{2017}{2018}\)
Đởn giản hết sẽ còn là:
\(\Rightarrow B=\frac{1}{2018}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
= \(\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\cdot\cdot\frac{19}{20}=\frac{1}{20}\)
=\(\frac{1}{2}.\frac{2}{3}.\frac{3}{4}......\frac{19}{20}\)
= đến đây bn xem trong thống kê hỏi đáp nhé
= :))
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\frac{3}{2}.\frac{4}{3}.\frac{5}{4}...\frac{99}{98}.\frac{100}{99}=\frac{3.4.5....99.100}{2.3.4...98.99}=\frac{100}{2}=50\)
=> A = 50