1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)

来源：学生作业帮助网 编辑：作业帮 时间：2024/07/13 13:22:47
1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
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1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)

1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
=0.5+1+1.5+2+...+20
=(0.5+20)+(1+19.5)+...+(10+10.5)
=20*20.5
=20*(20+0.5)
=400+10
=410

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