初一数学题啦！~谢谢大家帮忙！！！~

1、（1-3）+（5-7）+........（2001-2003）+2005
=-1002+2005=1003
2、1/2+1/4=3/4，3/4+1/8=7/8,7/8+1/16=15/16......
又规律可以看出最后答案为255/256
3、（1-2）+（3-4）+........（99-100）
=100/2*-1=-50
4、2/3+2/15+2/35+2/63+2/99
2/3=1-1/3,2/15=1/3-1/5,2/35=1/5-1/7,2/63=1/7-1/9,2/99=1/9-1/11
带入原式得1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11=10/11
5、5，-2, 3
0, 2, 4
1， 6，-1

1.
1-3+5-7+9-11+...+2001-2003+2005
=（5-3）+（9-7）+（13-11）......+(2005-2003)+1
=2*[(2005-3)/2+1]/2+1
=1002+1
=1003

2.
1/2+1/4+1/8+1/16+1/64+1/128+1/256
=255/256

3.
1-2+3-4+......+99-100
=-1*50
=-50

4.
2/3+2/15+2/35+2/63+2/99
=1/2(1-1/3+1/3-1/5+...+1/9-1/11)
=1/2(1-1/11)
=5/11

5.

-1.6,1
4,2,0
3,-2,5

1-3+5-7+9-11+...+2001-2003+2005
=（5-3）+（9-7）+（13-11）......+(2005-2003)+1
=2*[(2005-3)/2+1]/2+1
=1002+1
=1003
1/2+1/4+1/8+1/16+1/64+1/128+1/256
=255/256
1-2+3-4+......+99-100
=-1*50
=-50

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