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a,
\(\frac{45}{46}>\frac{2011}{2012}\)
b,
\(\frac{2010}{2011}< \frac{17}{16}\)
Hok tốt!
\(a,\frac{45}{46}\)và \(\frac{2011}{2012}\)
Ta có: \(1-\frac{45}{46}=\frac{1}{46};1-\frac{2011}{2012}=\frac{1}{2012}\)
\(\frac{1}{46}>\frac{1}{2012}\Rightarrow\frac{45}{46}>\frac{2011}{2012}\)
\(b,\frac{2010}{2011}\)và \(\frac{17}{16}\)
Ta có: \(\frac{2010}{2011}< 1;\frac{17}{16}>1\Rightarrow\frac{2010}{2011}< \frac{17}{16}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(1=\frac{45}{46}+\frac{1}{46}\)
\(1=\frac{2011}{2012}+\frac{1}{2012}\)
Vì \(\frac{1}{46}>\frac{1}{2012}\)\(\Rightarrow\)\(\frac{45}{46}< \frac{2011}{2012}\)
b)Vì 2010/2011 < 1 và 17/16 > 1 => 2010/2011 < 17/16
![](https://rs.olm.vn/images/avt/0.png?1311)
\(=\frac{16}{15}\times\frac{17}{16}\times\frac{18}{17}\times...\times\frac{2010}{2009}\times\frac{2011}{2010}\)
\(=\frac{1}{15}\times2011\)
\(=\frac{2011}{15}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
A = \(\dfrac{2008}{2009+2010+2011}+\dfrac{2009}{2009+2010+2011}+\dfrac{2010}{2009+2010+2011}\)
Ta có:
\(\dfrac{2008}{2009}>\dfrac{2008}{2009+2010+2011}\)
\(\dfrac{2009}{2010}>\dfrac{2009}{2009+2010+2011}\)
\(\dfrac{2010}{2011}>\dfrac{2010}{2009+2010+2011}\)
Từ 3 điều trên suy ra : A < B
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Trả lời:
\(\frac{2011\times2010-1}{2009\times2011+2010}\)
\(=\frac{2011\times\left(2009+1\right)-1}{2009\times2011+2010}\)
\(=\frac{2009\times2011+2011-1}{2009\times2011+2010}\)
\(=\frac{2009\times2011+2010}{2009\times2011+2010}\)
\(=1\)
\(\frac{2011\times2010-1}{2009\times2011+2010}\)
\(=\frac{2011\times2010-1}{2009\times2011+2011-1}\)
\(=\frac{2011\times2010-1}{2010\times2011-1}\)
\(=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
sửa lại : \(\frac{16}{15}\cdot\frac{17}{16}\cdot\frac{18}{17}\cdot...\cdot\frac{2010}{2009}\cdot\frac{2011}{2010}\)
\(=\frac{16\cdot17\cdot18\cdot...\cdot2010\cdot2011}{15\cdot16\cdot17\cdot...\cdot2009\cdot2010}\)
\(=\frac{2011}{15}\)