A = 2012 . 2014
A = 2012 . ( 2013 + 1 )
A = 2012 . 2013 + 2012
\(\Rightarrow\)A < 2012 . 2013 + 2013 = 2013.( 2012 + 1 ) = 2013 . 2013 = B
\(\Rightarrow A< B\)
Vậy A<B
!!!
xet A = 2012.2014
A= 2012 . [ 2013 +1 ]
A = 2012. 2013 + 2012
xet B = 2013 .2013
B= 2013 . [ 2012+ 1]
B=2013 .2012 + 2013
Co 2013.2012=2012.2013 va 2013 > 2012
nen A > B