Science

Math

Humanities

... and beyond

Socratic Meta
Featured Answers

Topics

What is the sum of this geometric series. #sum2(3)^( n-1)# for n=1 to 6?

1 Answer

Apr 13, 2017

#728#

Explanation:

Since

#a+ar+ar^2+cdots+ar^(n-1)=(a(1-r^n))/(1-r)#,

we have

#sum_{n=1}^6 2(3)^(n-1)=(2(1-3^6))/(1-3)=728#

I hope that this was clear.

Related questions

Impact of this question

1225 views around the world

You can reuse this answer
Creative Commons License