Why limit n-> infinity (3/4)^n = 0

  • Thread starter Thread starter Jbreezy
  • Start date Start date
  • Tags Tags
    Infinity Limit
Click For Summary

Homework Help Overview

The discussion revolves around the limit of the expression (3/4)^n as n approaches infinity, questioning why this limit equals zero. The subject area includes concepts from calculus, specifically limits and sequences.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the behavior of the sequence formed by (3/4)^n and question the reasoning behind the limit approaching zero. There are also inquiries about a different limit involving (1+k/n)^n and the implications of substitutions made in that context.

Discussion Status

The discussion is ongoing, with participants raising questions about the reasoning behind limits and substitutions. Some guidance is offered regarding the relationship between n and the variable u in the context of limits, but no consensus has been reached.

Contextual Notes

Participants express confusion over the assumptions made in the problems, particularly regarding the behavior of sequences and the implications of constants in limits as n approaches infinity.

Jbreezy
Messages
582
Reaction score
0
Why limit n--> infinity (3/4)^n = 0

Homework Statement



Quick question. Brain flagrance.

Homework Equations



Why limit n--> infinity (3/4)^n = 0

The Attempt at a Solution



?? Why is this. How do you know.
 
Physics news on Phys.org
Jbreezy said:

Homework Statement



Quick question. Brain flagrance.

Homework Equations



Why limit n--> infinity (3/4)^n = 0

The Attempt at a Solution



?? Why is this. How do you know.

Look at the sequence 3/4, (3/4)2, (3/4)3, and so on. What appears to be happening?
 
Got it. What about this? THanks
limit (1+k/n)^n as n->infinity

Just go here http://www.calcchat.com/book/Calculus-ETF-5e/
You have to put in chapter 9 section 1 and question 69. I just don't understand how they knew to make a substitution.
 
Ps then after they make the sub with u they write it as u goes to 0...huh?
 
Jbreezy said:
Got it. What about this? THanks
limit (1+k/n)^n as n->infinity

Just go here http://www.calcchat.com/book/Calculus-ETF-5e/
You have to put in chapter 9 section 1 and question 69. I just don't understand how they knew to make a substitution.
They are likely using a result from a previous problem. If so, the purpose of the substitution was to get the problem in that form.
 
Jbreezy said:
Ps then after they make the sub with u they write it as u goes to 0...huh?
For the substitution u = k/n, if n → ∞, what does u do?
 
Last edited:
Stays the same? Isn't k a constant? So OH lol so you take the limit as u goes to 0 because as k/n goes to infinity u goes to 0? I say that right?
 
Sorry, I was typing faster than I was thinking. I meant "what does u do" as n → ∞?(I edited my earlier post.)
Jbreezy said:
Stays the same? Isn't k a constant? So OH lol so you take the limit as u goes to 0 because as k/n goes to infinity u goes to 0? I say that right?
No, you didn't. As k/n goes to infinity, so does u, since u = k/n. The way to look at it is, as n → ∞, then the fraction k/n → 0.
 
Mark44 said:
Sorry, I was typing faster than I was thinking. I meant "what does u do" as n → ∞?(I edited my earlier post.)
No, you didn't. As k/n goes to infinity, so does u, since u = k/n. The way to look at it is, as n → ∞, then the fraction k/n → 0.

This always bugs me, because assuming k > 0, as n → ∞, k/n → 0 from the right.
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 23 ·
Replies
23
Views
2K
  • · Replies 24 ·
Replies
24
Views
2K
Replies
2
Views
1K
  • · Replies 7 ·
Replies
7
Views
5K
  • · Replies 2 ·
Replies
2
Views
1K
Replies
5
Views
2K
  • · Replies 12 ·
Replies
12
Views
2K