作业帮1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
来源：学生作业帮助网 编辑：作业帮 时间：2024/11/18 11:19:12
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1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
=1/2(1/2-1/3+1/3-1/4+…………+1/15-1/16)
=1/2(1/2-1/16)
=7/32
1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
=2(1/2-1/3+1/3-1/4+…………+1/15-1/16)
=2(1/2-1/16)
=7/8