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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:
B=2012/(2013+2014)+2013/(2013+2014)
Xét từng số hạng của B:
2012/(2013+2014)<2012/2013
2013/2013+2014<2013/2014
=>B=2012/(2013+2014)+2013/(2013+2014)<2012/2013+2013/2014=A
=>B<A
![](https://rs.olm.vn/images/avt/0.png?1311)
A = 8 15 . 21 12 , B = ( − 3 ) 5 . ( − 7 ) 9 ; A = 8 15 . 21 12 = 8.21 15.12 = 4.2.3.7 3.5.4.3 = 14 15 B = ( − 3 ) 5 . ( − 7 ) 9 = ( − 3 ) . ( − 7 ) 5.9 = 3.7 5.3.3 = 7 15 V ì 14 15 > 7 15 n ê n A > B
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có A = 3 10 . 4 9 = 2 15 ; B = 4. 3 8 = 3 2 mà 2 15 < 3 2 nên A < B
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:\(\frac{2018}{2019}\)<1\(\Rightarrow\)\(\frac{2018}{2019}\)>\(\frac{2018}{2019+2020}\)
\(\frac{2019}{2020}\)<1\(\Rightarrow\)\(\frac{2019}{2020}\)>\(\frac{2019}{2019+2020}\)
\(\Rightarrow\)\(\frac{2018}{2019}\)+\(\frac{2019}{2020}\)>\(\frac{2018}{2019+2020}\)+\(\frac{2019}{2019+2020}\)=\(\frac{2018+2019}{2019+2020}\)
\(\Rightarrow\)A>B
Vậy A>B
Ta có :\(A=\frac{2018}{2019}+\frac{2019}{2020}\)
\(B=\frac{2018+2019}{2019+2020}\)
\(B=\frac{2018}{2019+2020}+\frac{2019}{2019+2020}\)
Ta thấy :
\(\frac{2018}{2019}>\frac{2018}{2019+2020}\left(2019< 2019+2020\right)\)
\(\frac{2019}{2020}>\frac{2019}{2019+2020}\left(2020< 2019+2020\right)\)
\(\Rightarrow\frac{2018}{2019}+\frac{2019}{2020}>\frac{2018+2019}{2019+2020}\)
Vậy \(A>B\)
~ Thiên Mã ~
![](https://rs.olm.vn/images/avt/0.png?1311)
A = 2483 − 13 4966 − 26 = 191.13 − 13.1 26.191 − 26.1 = 13.190 26.190 = 1 2 = 18 36
B = 2727 − 101 7575 + 303 = 27.101 − 101.1 75.101 − 3.101 = 101.26 101.72 = 13 36
Vậy A > B
![](https://rs.olm.vn/images/avt/0.png?1311)
a ) A = 8 15 . 21 12 , B = ( − 3 ) 5 . ( − 7 ) 9 ; A = 8 15 . 21 12 = 8.21 15.12 = 4.2.3.7 3.5.4.3 = 14 15 B = ( − 3 ) 5 . ( − 7 ) 9 = ( − 3 ) . ( − 7 ) 5.9 = 3.7 5.3.3 = 7 15 V ì 14 15 > 7 15 n ê n A > B
b) học sinh tự làm
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có
B= 2000/2001+2002 + 2001/2001+2002. Mà 2000/2001+2002 < 2000/2001 và 2001/2001+2002 < 2001/2002. Nên 2000/2001+2002 + 2001/ 2001+2002 < 2000/2001 + 2001/2002. Hay 2000+2001/ 2001+2002 < 2000/2001 + 2001/2002 Suy ra B < A
![](https://rs.olm.vn/images/avt/0.png?1311)
*Thắc mắc)Biểu thức A và B đâu bạn?
Where are two "biểu thức"? I don't see they on my computer. Can you help me find they?