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
b) Ta có A=2009.2011=2009(2010+1)=2009.2010+2009
B=20102=2010.2010=(2009+1)2010=2009.2010+2010
Mà 2009.2010+2009<2009.2010+2010
Nên A<B
a)Ta có: 2.A= 21+22+23+24+...+22011
Mà A= 20+21+22+23+...+22010
A=22011-1
vâỵ A=B
b)Ta có :A=2009.2011
A= 2009.(2010+1)
A=2009.2010+2009
B=20102=2010.2010
B=(2009+1).2010
B=2009.2010+2010
Vậy A<B
c)Ta có : 52n=(52)n=25n
25n=(25)n=32n
Vì 25<32 => 25n<32n
Vậy 52n<25n
d)7245-7244=7244.72-7244=7244.(72-1)
7244-7243=7243.72-7243=7243.(72-1)
Vì 7244.(72-1) >7243.(72-1)
Nên 7245-7244>7244-7243
NHỚ KICK CHO TUI NHA
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