A = 2008 x 2008

= (2007 + 1) x 2008

= 2007 x 2008 + 2008 x 1

= 2007 x 2008 + 2008

B = 2007 x 2009

= 2007 x (2008 +1)

= 2007 x 2008 + 2007 x 1

= 2007 x 2008 + 2007

Vì 2008 < 2007 => A > B

Ta có \(B=2007\times2009\)\(=\left(2008-1\right)\times\left(2008+1\right)\)\(=2008\times2008+2008-2008-1\)\(=2008\times2008-1\)

Vì \(-1< 0\)nên \(2008\times2008-1< 2008\times2008\)hay \(B< A\)

A > B

<

2008 x 2008 > 2007 x 2009

2008 x 2008 lớn hơn 2007 x 2009 1 đơn vị

2007 x 2009 

= ( 2008 - 1 ) x ( 2008 + 1 )

= ( 2008 ) ²  - 1²

Ta thấy 2008 x 2008 = 2008² 

=> 2008 x 2008 > 2007 x 2009 

A = 2007 x 2007

A = 2004 x 2007 + 3 x 2007

B = 2004 x 2008

B = 2004 x (2007 + 1)

B = 2004 x 2007 + 2004

Vì 2004 x 2007 = 2004 x 2007 và 3 x 2007 > 2004 nên A > B

3, A= 2007 X 2009

  = 2007 X (2008+ 1)

  = 2007 X 2008+ 2007

B= 2008 X 2008

  = 2008 X (2007+ 1)

  = 2008 X 2007+ 2008

Vì 2007 < 2008 nên 2008 X 2007+ 2007 < 2008 X 2007+ 2008

Vậy A < B

\(B=2004\times2008\)

\(B=\left(2007-3\right)\times\left(2007+1\right)\)

\(B=\left(2007-3\right)\times2007+\left(2007-3\right)\)

\(B=2007\times2007-3\times2007+2007-3\)

\(B=2007\times2007-3\times2007+2004\)\(>2007\times2007=A\)

          Vậy B > A

    _Hok tốt_

!!!

a)\(A=2007\times2007\)

\(A=2004\times2007+3\times2007\)

b) \(B=2004\times2008\)

\(B=2004\times\left(2007+1\right)\)

\(B=2004\times2007+2004\)

Vì 2004 x 2007 = 2004 x 2007 và 3 x 2007 > 2004 nên A > B

tôi thích hoa hồng sai kìa

Vì 2006/2007 ; 2007/2008 ; 2008/2009 ; 2009/2010 đều bé hơn 1 nên:

2006/2007 + 2007/2008 + 2008/2009 + 2009/2010 < 1 + 1 + 1 + 1 = 4.

Vậy ...