\(2009\times2011=\left(2010-1\right)\times\left(2010+1\right)=2010\times2010\)
\(2010\times2010\)
\(\Rightarrow2009\times2011=2010\times2010\)
A= 2009*2011= 2009*(2010+1)=2009*2010 +2009
B=2010*2010= (2009+1)*2010=2009*2010 +2010
=> A<B
Ta có:
A=2009x2011
A=2009x(2010+1)
A=2009x2010+2009
B=2010x2010
B=(2009+1)x2010
B=2009x2010+2010
Vì 2009x2010=2009x2010 và 2009<2010 nên 2009x2010+2009<2009x2010+2010 =>A<B