Ta so sánh 2009/2010 và 2010/2009
Ta có 2009/2010<1<20010/2009
=>2009/2010<2010/2009 => -2009/2010 > 2010/- 2009
 

vi \(\frac{-2009}{2010}>\frac{-2010}{1010}=1\)

\(\frac{2010}{-2009}=\frac{-2010}{2009}

\(\dfrac{2009}{2010}=\dfrac{2009\cdot10001}{2010\cdot10001}=\dfrac{20092009}{20102010}\)

\(\dfrac{2009}{2010}=\dfrac{20092009}{20102010}\)

sẽ bằng nhau 

câu hỏi tương tự

Ta có :

\(N=\frac{2009^{2010}-2}{2009^{2011}-2}< \frac{2009^{2010}-2+2011}{2009^{2011}-2+2011}\)

\(=\frac{2009^{2010}+2009}{2009^{2011}+2009}=\frac{2009.\left(2009^{2009}+1\right)}{2009.\left(2009^{2010}+1\right)}\)

\(=\frac{2009^{2009}+1}{2009^{2010}+1}=M\)

Vậy \(M>N\)

Ta có: \(B< 1\)

\(\Rightarrow B< \frac{2009^{2010}-2+3}{2009^{2011}-2+3}=\frac{2009^{2010}+1}{2009^{2011}+1}\left(1\right)\)

Mà \(\frac{2009^{2010}+1}{2009^{2011}+1}< 1\)

\(\Rightarrow\frac{2009^{2010}+1}{2009^{2011}+1}< \frac{2009^{2010}+1+2008}{2009^{2011}+1+2008}=\frac{2009^{2010}+2009}{2009^{2011}+2009}=\frac{2009\left(2009^{2009}+1\right)}{2009\left(2009^{2010}+1\right)}=\frac{2009^{2009}+1}{2009^{2010}+1}=A\left(2\right)\)

Từ (1) và (2) suy ra A > B

Ta có :

$B=\genfrac{}{}{0ex}{}{2009^{2010}-2}{2009^{2011}-2}<1$

$\iff B<\genfrac{}{}{0ex}{}{2009^{2010}-2+2011}{2009^{2011}-2+2011}=\genfrac{}{}{0ex}{}{2009^{2010}+2009}{2009^{2011}+2009}=\genfrac{}{}{0ex}{}{2009\left(2009^{2009}+1\right)}{2009\left(2009^{2010}+1\right)}=\genfrac{}{}{0ex}{}{2009^{2009}+1}{2009^{2010}+1}=A$

$\iff A>B$

Ta có :

\(B=\dfrac{2009^{2010}-2}{2009^{2011}-2}< 1\)

\(\Leftrightarrow B< \dfrac{2009^{2010}-2+2011}{2009^{2011}-2+2011}=\dfrac{2009^{2010}+2009}{2009^{2011}+2009}=\dfrac{2009\left(2009^{2009}+1\right)}{2009\left(2009^{2010}+1\right)}=\dfrac{2009^{2009}+1}{2009^{2010}+1}=A\)

\(\Leftrightarrow A>B\)