Ta có: 2015 > 1
=> 2015 * 2015 > 1
2011 > 1
2019 > 1
=> 2011 * 2019 > 1
=> ( 2015 * 2015 ) * ( 2011 * 2019 ) > 1
=> A > 1
A = ( 2015 x 2015 ) x ( 2011 x 2019 )
Ta có:
2015 > 1; 2011 > 1 ; 2019 > 1
\(\Rightarrow\)( 2015 x 2015 ) x ( 2011 x 2019 ) > 1
Vậy A > 1