2011×20002000-2000×20112011
=2011*2*10001000-2000*2011*10001
=2011*2*10001000-2*1000*2011*10001
=2011*2*10001000-2*2011*10001000
=0
2011×20002000-2000×20112011
=2011*2*10001000-2000*2011*10001
=2011*2*10001000-2*1000*2011*10001
=2011*2*10001000-2*2011*10001000
=0