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0.10+0.12+0.14+0.16+...+0.88+0.90=?
题目详情
0.10+0.12+0.14+0.16+...+0.88+0.90=?
▼优质解答
答案和解析
等差数列求和
(首项+末项)*项数/2
=(0.1+0.9)* 41/2
=20.5
(首项+末项)*项数/2
=(0.1+0.9)* 41/2
=20.5
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