\(2004.2004\) \(2005.2003\)
\(=\left(2003+1\right).2004\) \(=\left(2004+1\right).2003\)
\(=2003.2004+2004\) \(=2004.2003+2003\)
ta thấy \(2003.2004=2004.2003\)
mà \(2004>2003\)
\(\Rightarrow2003.2004+2004>2004.2003+2003\)
\(\Rightarrow2004.2004>2005.2003\)
Có: 2004 x 2004 = (2003+1) x 2004 = 2003 x 2004 + 2004 = (2003 x 2004 + 2003) + 1 = 2003 x (2004+1) + 1 = 2003 x 2005 + 1
=> 2004 x 2004 > 2003 x 2005
Tk mk nha
vì : 2004*2004=4016016
2005*2002=4014010
suy ra 2002*2005<2004*2004
\(2005\times2003\)
\(=\left(2004+1\right)\left(2004-1\right)\)
\(=2004\left(2004-1\right)+\left(2004-1\right)\)
\(=2004^2-2004+2004-1\)
\(=2004^2-1\)\(< 2004^2=2004\times2004\)
\(2004\times2004=4016016\)
\(2005\times2003=4016015\)
Mà 4016016 > 4016015 nên \(2004\times2004>2005\times2003\)