Răspuns :
1 999 • 2 000 - 1998 • 1999 - 2 • 1998 = 2
= 1 999 • ( 2 000 - 1 998 ) - 2 • 1 998 =
= 1 999 • 2 - 2 • 1 998 =
= 2 • ( 1 999 - 1 998 ) =
= 2 • 1 =
= 2
1 999 • 2 000 - 1998 • 1999 - 2 • 1998 = 2
= 1 999 • ( 2 000 - 1 998 ) - 2 • 1 998 =
= 1 999 • 2 - 2 • 1 998 =
= 2 • ( 1 999 - 1 998 ) =
= 2 • 1 =
= 2