简便计算1997²-1996×1998分之1997
问题描述：
简便计算1997²-1996×1998分之1997
答
令a=1997
则原式=a/[a²-(a-1)(a+1)]
=a/[a²-(a²-1)]
=a/(a²-a²+1)
=a
=1997