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Find the sum of the first 20 terms of the series. 1+3+9+27+...
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High School Teacher
This is geometric series with first term `a_1=1` and ratio `r=3`.
Sum of the first `n` terms of geometric series is
Hence sum of the first 20 terms is ` `
Posted by tiburtius on May 2, 2013 at 7:12 PM (Answer #1)
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