[Calculus] Sequence Limits: n -> infinity (n/n^n)(Use Sandwich Rule?)

In summary, the question asks to use the Sandwich Rule to find the limit of the sequence lim n>infinity (a_n), where a_n is given by n!/n^n. By examining the terms, it is clear that n^n grows much faster than n!, resulting in a limit of 0. However, to use the Sandwich Rule, we must find two functions to bound n!/n^n between. By expanding the expression, we can see that n!/n^n can be written as a product of terms that approach 1 as n approaches infinity. This may provide some ideas for choosing the bounding functions.
  • #1
raaznar
6
0

Homework Statement


Use sandwich Rule to find the limit lim n> infinity (a_n) of the sequences, for which the nth term, a_n, is given.


Homework Equations


[itex] ^{lim}_{n\rightarrow∞}\frac{n!}{n^{n}}[/itex]


The Attempt at a Solution


I know by just looking at it, n^n Approaches infinity much faster than n! which results in limit approaching 0, which is the answer. But the question says to use Sandwich Rule? I don't know which 2 functions to use to bound n!/n^n between? Usually if there was a sin function, I could start with it between -1 and 1. But I don't know where to start for this question?
 
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  • #2
raaznar said:

Homework Statement


Use sandwich Rule to find the limit lim n> infinity (a_n) of the sequences, for which the nth term, a_n, is given.

Homework Equations


[itex] ^{lim}_{n\rightarrow∞}\frac{n!}{n^{n}}[/itex]

The Attempt at a Solution


I know by just looking at it, n^n Approaches infinity much faster than n! which results in limit approaching 0, which is the answer. But the question says to use Sandwich Rule? I don't know which 2 functions to use to bound n!/n^n between? Usually if there was a sin function, I could start with it between -1 and 1. But I don't know where to start for this question?

Expand it. n!/n^n=(n/n)*((n-1)/n)*((n-2)/n)*...*(3/n)*(2/n)*(1/n). Does that give you any ideas?
 

What is the purpose of using the Sandwich Rule when evaluating sequence limits?

The Sandwich Rule, also known as the Squeeze Theorem, is used to evaluate sequence limits by comparing the given sequence to two other sequences with known limits. This helps to determine the limit of the given sequence and prove its convergence or divergence.

How do you use the Sandwich Rule to evaluate the limit of a sequence as n approaches infinity?

To use the Sandwich Rule, you need to find two other sequences that are always greater than or equal to the given sequence and two other sequences that are always less than or equal to the given sequence. Then, you can take the limit of these two "sandwiching" sequences and if they have the same limit, that will be the limit of the given sequence.

What are the steps for using the Sandwich Rule to evaluate a sequence limit?

The first step is to identify the given sequence and determine if it is increasing or decreasing. Then, find two other sequences that are always greater than or equal to the given sequence and two other sequences that are always less than or equal to the given sequence. Next, take the limit of these two "sandwiching" sequences and if they have the same limit, that will be the limit of the given sequence.

Can the Sandwich Rule be used to evaluate the limit of any sequence?

No, the Sandwich Rule can only be used to evaluate the limit of sequences that approach infinity. It cannot be used for sequences that approach a finite number or a limit as n approaches a specific value.

Are there any limitations or exceptions when using the Sandwich Rule to evaluate sequence limits?

Yes, there are some limitations and exceptions when using the Sandwich Rule. It cannot be used if the two "sandwiching" sequences have different limits or if the given sequence is not bounded by the other two sequences. Additionally, the Sandwich Rule may not work for more complex sequences that require alternative methods of evaluation.

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