(+1)+(-2)+(+3)+(-4)+……+(+2005)+(-2006)+2007

来源：学生作业帮助网编辑：作业帮时间：2024/05/08 18:28:35

(+1)+(-2)+(+3)+(-4)+……+(+2005)+(-2006)+2007
(+1)+(-2)+(+3)+(-4)+……+(+2005)+(-2006)+2007

(+1)+(-2)+(+3)+(-4)+……+(+2005)+(-2006)+2007
(+1)+(-2)+(+3)+(-4)+……+(+2005)+(-2006)+2007
=(1+3+5+...+2007)-(2+4+6+...+2006)
=[(1+2007)*1004/2]-[(2+2006)*1003/2]
=1006008-1007012=-1004

1004

1 2 3 4 1 2 3 4 1 2 3 4 1,2,3,4, 1 2 3 4 1 2 3 4 1,2,3,4, 1,2,3,4, 1,2,3,4, 1,2,3,4, 1 2 3 4 1,2,3,4, 1,2,3,4, 1,2,3,4, 1、2、3、4 1+2+3×4 1,2,3,4 1+2+3+4+.