• Support PF! Buy your school textbooks, materials and every day products Here!

Sum of infinite geometric series

  • #1
1. Homework Statement



2. Homework Equations



3. The Attempt at a Solution

I don't get what I am doing wrong here, I have attached my solution below. The solution manual have their answer as 3e/(3-e). Thanks!
 

Attachments

Answers and Replies

  • #2
Gib Z
Homework Helper
3,344
4
Try posting the question in LaTex from now on, attachments have to be approved and put extra load on the moderators.
 
  • #3
I type really slow in Latex, I type faster in Mathtype in word, that's why I included as an attachment. Sorry. Anyhow, here is the link to that attachment

http://p3t3rl1.googlepages.com/Eqn001.gif
 
  • #4
tiny-tim
Science Advisor
Homework Helper
25,789
249
Hi motornoob101!

You got confused with your second ∑.

It should be e∑(e/3)^x-1, shouldn't it? :rolleyes:
 
  • #5
Erm I don't think get it.. So I have e^(x-1) which is same as (e^x) (e^-1) and e^-1 is (1/e) no?
 
  • #6
HallsofIvy
Science Advisor
Homework Helper
41,738
899
You have, skipping over your second term which simply makes no sense,
[tex]\frac{e^n}{3^{n-1}}= \frac{1}{e}\left(\frac{e}{3}\right)^{n-1}[/tex]
which is wrong- you have factored and e out of the numerator: it should be
[tex]\frac{e^n}{3^{n-1}}= e\left(\frac{e}{3}\right)^{n-1}[/tex]
 
  • #7
Ohh I see. Thanks.
 

Related Threads for: Sum of infinite geometric series

  • Last Post
Replies
6
Views
2K
Replies
5
Views
2K
Replies
10
Views
4K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
2
Views
509
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
10
Views
826
  • Last Post
Replies
4
Views
2K
Top