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40 votes
40 votes
Does the series 3+9+27+81+…. diverge or converge

User Dunbarx
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2 Answers

23 votes
23 votes
this series diverges
User Tweetysat
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21 votes
21 votes

Given the series


3+9+27+81+\cdots

which is a geometric series with first term 3 and common ratio 3.

A geometric series conveges if and only if |r| < 1, where r is the common ratio. Here, r = 3 > 1. So, the given geometric series diverges.

User Sambardo
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2.9k points