问题 填空题
数列0.
••
18
,0.0000
••
18
,…的前n项和______及各项和S=______.
答案

依题意可知数列0.

••
18
,0.0000
••
18
,…以0.
••
18
为首项,0.01为公比的等比数列

∴前n项和Sn=

0. 
••
18
(1-0.01n)
1-0.01
=
0.
••
18
(1-0.01n)
0.99

∴S=

lim
n→∞
Sn=
0.
••
18
1-0.01
=
0.
••
18
0.99

故答案为

0.
••
18
(1-0.01n)
0.99
0.
••
18
0.99

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