利用乘法分配率,得:
=1999X2+1997X2+1995X(-3)
=1992X2+1997X2-1995X2-1995
=(1999+1997-1995)X2-1995
=2001X2-1995
=4002-1995
=2007
满意给个满分...
(*^__^*) 嘻嘻……最后加分..
呵呵...开玩笑