Răspuns :
2001·2000-1999·2000-2·1999=
=2000·(2001-1999)-3998=
=2000·2-3998=
=4000-3998=
=2
=2000·(2001-1999)-3998=
=2000·2-3998=
=4000-3998=
=2
2001*2000=4002000 1999*2000= 3998000 2*1999= 3998 4002000-3998000-3998 =2