1996 x 1995 - 996 - 1000 - 1996 x 1994
= 1996 x 1995 - 1996 - 1996 x 1994
= 1996 ( 1995 - 1 - 1994 )
= 1996 . 0
= 0
dễ
1996x1995-996-1000-1996x1994
= 1996 x 1995 - ( 996 + 1000 ) - 1996 x 1994
= 1996 x 1995 - 1996 x 1 - 1996 x 1994
= 1996 x ( 1995 - 1 - 1994 )
= 1996 x 0
= 0