1/1998乘1999+1/1999乘2000+.1/2005乘2006+1/2006
问题描述:
1/1998乘1999+1/1999乘2000+.1/2005乘2006+1/2006
急用!
答
1/(1998×1999)+1/(1999×2000)+.1/(2005×2006)+1/2006
=(1/1998-1/1999)+(1/1999-1/2000)+……+(1/2005-1/2006)-1/2006
=1/1998