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![](https://rs.olm.vn/images/avt/0.png?1311)
\(Q=\frac{2010+2011+2012}{2011+2012+2013}\)
\(Q=\frac{2010}{2011+2012+2013}+\frac{2011}{2011+2012+2013}+\frac{2012}{2011+2012+2013}\)
Ta có :
\(\hept{\begin{cases}\frac{2010}{2011}>\frac{2010}{2011+2012+2013}\\\frac{2011}{2012}>\frac{2011}{2011+2012+2013}\\\frac{2012}{2013}>\frac{2012}{2011+2012+2013}\end{cases}}\)
\(\Rightarrow P>Q\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Xét A=1+2+22+23+...+22010
2A=2+22+23+24+...+22011
2A-A=22011-1
<=> A=22011-1=B
![](https://rs.olm.vn/images/avt/0.png?1311)
b) A = 2009 . 2011
A = 2009 . ( 2010 + 1 )
A = 2009 . 2010 + 2009
B = 20102
B = 2010 . 2010
B = ( 2009 + 1 ) . 2010
B = 2009 . 2010 + 2010
Mà 2009 . 2010 + 2009 < 2009 . 2010 + 2010
Vậy A < B
d tương tự
c) 52n và 25n
52n = 25n
25n = 32n
Mà 25n < 32n
Vậy 52n < 25n
a) A = 20 + 21 + 22 + 23 + ............ + 22010
2A = 21 + 22 + 23 + 24 + .............. + 22011
2A - A = ( 21 + 22 + 23 + 24 + ............... + 22011 ) - ( 20 + 21 + 22 + 23 + ................ + 22010 )
A = 22011 - 1
Mà 22011 - 1 = 22011 - 1
Vậy A = B
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=2^0+2^1+2^2+...+2^{2010}\)
=>\(2A=2^1+2^2+2^3+...+2^{2011}\)
=> \(2A-A=\left(2^1+2^2+2^3+...+2^{2011}\right)-\left(2^0+2^1+2^2+...+2^{2010}\right)\)
=> \(A=2^{2011}-2^0=2^{2011}-1=B\)
![](https://rs.olm.vn/images/avt/0.png?1311)
2^0=1
A=1+2^1+2^2+2^3+.........+2^2010
A.2=2.(1+2^1+2^2+...+2^2010)
A.2=2.1+2.2^1+.......+2.2^2010
A.2=2+2^2+2^3+....+2^2010+2^2011
A=A.2-A=2^2011-1 (lấy số cuối trừ số đầu nha)
A=B
![](https://rs.olm.vn/images/avt/0.png?1311)
Gọi tổng đó là A, ta có
\(A=2^0+2^1+2^2+...+2^{2010}\)
\(2A=A=2^1+2^2+2^3+...+2^{2011}\)
\(2A-A=2^{2011-1}\)
\(A=2^{2011}-1\)
Vậy A bằng 2^2011-1
cho A=2^0+2^1+2^2+...+2^2010
2A=2^1+2^2+2^3+...+2^2011
2A-A=(2^1+2^2+2^3+...+2^2011)-(2^0+2^1+2^2+...+2^2010)
A=2^2011-2^0
A=2^2011-1
Vậy A=B
![](https://rs.olm.vn/images/avt/0.png?1311)
bạn tính P=2^2011-2
suy ra : P<Q
2P = 2 + 2^2 + ... + 2^2011
2P - P = (2 - 2) + (2^2 - 2^2) + ...... + (2^2010 - 2^2010) + 2^2011 - 1
P = 2^2011 - 1
2^2011 > 2^2011 - 1
Vậy P < Q
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