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Cho A=\(\dfrac{2003}{2004}\)+\(\dfrac{2004}{2005}\); B=\(\dfrac{2003+2004}{2004+2005}\)
Ta có: B=\(\dfrac{2003}{2004+2005}\)+\(\dfrac{2004}{2004+2005}\)
Vì: \(\dfrac{2003}{2004+2005}< \dfrac{2003}{2004}\)
\(\dfrac{2004}{2004+2005}< \dfrac{2004}{2005}\)
=>\(\dfrac{2003}{2004+2005}+\dfrac{2004}{2004+2004}< \dfrac{2003}{2004}+\dfrac{2004}{2005}\)
=>\(\dfrac{2003+2004}{2004+2005}< \dfrac{2003}{2004}+\dfrac{2004}{2005}\)
=>B<A
Vậy B<A
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{2006\times2005-1}{2004\times2006+2005}=\dfrac{2006\times\left(2004+1\right)-1}{2004\times2006+2005}\)
\(=\dfrac{2004\times2006+2006-1}{2004\times2006+2005}=\dfrac{2004\times2006+2005}{2004\times2006+2005}\)
\(=1\)
\(18\times\left(\dfrac{19191919+88888}{21212121+99999}\right)=18\times\left(\dfrac{19}{21}+\dfrac{8}{9}\right)\)
\(=18\times\dfrac{113}{63}=\dfrac{226}{7}=32\dfrac{2}{7}\)
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\(A=\dfrac{2004^{2005}+1}{2004^{2005}-2004}>1>\dfrac{2004^{2005}}{2004^{2005}+2004}=B\)
Vậy A > B
Ta có :
\(\dfrac{2004^{2005}+1}{2004^{2005}-2004}>1>\dfrac{2004^{2005}}{2004^{2005}+2004}\)
\(\Rightarrow\) \(A>1>B\)
\(\Rightarrow\) \(A>B\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(2004A=\frac{2004^{2004}+2004}{2004^{2004}+1}=1+\frac{2003}{2004^{2004}+1}\)
\(2004B=\frac{2004^{2005}+2004}{2004^{2005}+1}=1+\frac{2003}{2004^{2005}+1}\)
\(\frac{2003}{2004^{2004}+1}>\frac{2003}{2004^{2005}+1}\)
\(\Rightarrow2004A>2004B\)
\(\Rightarrow A>B\)
2004A=\(\frac{2004^{2004}+2004}{2004^{2004}+1}\)
\(\frac{2004^{2004}+2004}{2004^{2004}+1}-1=\frac{2003}{2004^{2004}+1}\)
2004B=\(\frac{2004^{2005}+2004}{2004^{2005}+1}\)
\(\frac{2004^{2005}+2004}{2004^{2005}+1}-1=\frac{2003}{2004^{2005}+1}\)
Ta thấy :\(\frac{2003}{2004^{2004}+1}>\frac{2003}{2004^{2005}+1}\)
=> \(2004A>2004B\)
Vậy \(A>B\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Đặt \(A=\dfrac{2003.2004-1}{2003.2004}\) và \(B=\dfrac{2004.2005-1}{2004.2005}\)
Ta có : \(A=\dfrac{2003.2004-1}{2003.2004}=\dfrac{2003.2004}{2003.2004}-\dfrac{1}{2003.2004}\)
\(=1-\dfrac{1}{2003.2004}\)
\(B=\dfrac{2004.2005-1}{2004.2005}=\dfrac{2004.2005}{2004.2005}-\dfrac{1}{2004.2005}\)
\(=1-\dfrac{1}{2004.2005}\)
Vì \(\dfrac{1}{2003.2004}>\dfrac{1}{2004.2005}\Rightarrow1-\dfrac{1}{2003.2004}< 1-\dfrac{1}{2004.2005}\)
Nên \(A< B\)
Vậy \(\dfrac{2003.2004-1}{2003.2004}< \dfrac{2004.2005-1}{2004.2005}\)
~ Học tốt ~
![](https://rs.olm.vn/images/avt/0.png?1311)
\(B=\dfrac{2005}{x^m}+\dfrac{2003}{x^n}=\dfrac{2004}{x^m}+\dfrac{1}{x^m}+\dfrac{2004}{x^n}-\dfrac{1}{x^n}=A+\left(\dfrac{1}{x^m}-\dfrac{1}{x^n}\right)\)
\(\Rightarrow A< B\)
mình ko bt đúng hay sai nữa
Đáp án
\(\dfrac{\text{2005 x 2004 - 1}}{\text{2003 x 2005 + 2004}}\)
= 1
#hoctot
Tick cho mình nếu thấy đúng nhé
= -1/2003