Geometric series problem

  • Thread starter Jimmy84
  • Start date
  • #1
191
0
Geometric series problem urgent

Homework Statement



Calculate the geometric series of Ʃfrom n=1 to infinity of 1/n

Homework Equations





The Attempt at a Solution


I dont know how to start solving, how can I solve this? I have test about this tomorrow I really need some help please.
 

Answers and Replies

  • #2
33,732
5,422


First off, what is a geometric series? Are you sure that your series is a geometric series?
 
  • #3
191
0


First off, what is a geometric series? Are you sure that your series is a geometric series?
the formula is Ʃ from n=0 to ∞ of a(r)^n is equal to a/(1-r)

I was told to use the geoemtric series and to solve for that. but I dont know any general process or any way to do that. how can I start to solve that?
 
  • #4
33,732
5,422


The general term of a geometric series looks like this: ark. Does your series look like this?

It would be helpful to see the exact wording of your problem. What you have makes almost no sense.
 
  • #5
191
0


The general term of a geometric series looks like this: ark. Does your series look like this?

It would be helpful to see the exact wording of your problem. What you have makes almost no sense.
thats what I have there arent many details i solved some similar problems for instance

Ʃ from n = 0 to ∞ of 1/2^n by subsituing this in the a/(1-r) expression the result was 2

but on this problem I dont see how could I make such a substitution.
 
  • #6
SammyS
Staff Emeritus
Science Advisor
Homework Helper
Gold Member
11,315
1,006


Homework Statement



Calculate the geometric series of Ʃfrom n=1 to infinity of 1/n

Homework Equations





The Attempt at a Solution


I dont know how to start solving, how can I solve this? I have test about this tomorrow I really need some help please.
Are you sure that the word 'geometric' is in the problem in your book , wherever you got it.

This is a well known series that doesn't converge.
 
  • #7
191
0


Are you sure that the word 'geometric' is in the problem in your book , wherever you got it.

This is a well known series that doesn't converge.
Yes it is there
 
  • #8


Ʃfrom n=1 to infinity of 1/n..this is harmonic series where the n is to the power of 1..
i just learned this in my class
 
  • #9
SammyS
Staff Emeritus
Science Advisor
Homework Helper
Gold Member
11,315
1,006


...

This is a well known series that doesn't converge.
Writing out the first bunch of terms gives:

1 + 1/2

 + 1/3 + 1/4     This is greater than 1/2, because 1/3 > 1/4

 + 1/5 + 1/6 + 1/7 + 1/8    > 1/2, because each fraction is at least 1/8

 + 9 + 1/10 + 1/11 + 1/12 + 1/13 + 1/14 + 1/15 + 1/16  > 1/2, because each fraction is at least 1/16

 + ...

If you go far enough, you can exceed any number you like.
 
  • #10
33,732
5,422


Moderator's note: Thread moved to Calculus & Beyond section.
 
  • #11
2,571
1


This is a famous series...you will drill this into your head.
 
  • #12
2,571
1


Actually what are you calculating...? The sum? the convergence/divergence? limt?
 

Related Threads on Geometric series problem

  • Last Post
Replies
1
Views
683
  • Last Post
Replies
4
Views
3K
Replies
3
Views
3K
  • Last Post
Replies
7
Views
939
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
5
Views
763
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
4
Views
2K
Top