Convergence of Sequence: (n^2)/(e^n)

In summary, the conversation discusses the convergence of the sequence (n^2)/(e^n) and the solution being e/(e-1). However, the limit of the sequence as n goes to infinity is 0. The use of L'Hôpital's rule and confirmation from Wolfram Alpha is mentioned, as well as the question of whether the sequence converges. The correct answer is yes, and the question that the book states e/(e-1) as the answer to is not fully stated.
  • #1
k_squared
64
0
NEVERMIND! IT IS 0! I SOMEHOW WAS STARING AT THE WRONG ANSWER SHEET FOR A LITTLE BIT! THANK YOU!

1. Homework Statement

Determinte whether the sequence converges or diverges:
(n^2)/(e^n)2. Homework Equations

The book says that the solution is: e/(e-1).

However, the limit of the equation y=(n^2)/(e^n) as n goes to infinity is 0.

I don't know why I can't seem to apply the theorem that:

If the limit as x goes to infinity of f(x) = L and f(n)= an, then the limit of an as x approaches infinity is L.

3. The Attempt at a Solution

I used L'Hôpital's rule to prove the limit is 0. Wolfram alpha confirms this.
 
Last edited:
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  • #2
The question is whether the sequence converges, so the answer would be yes or no, right? What question does your book say e/(e-1) is the answer to? You are correct that the sequence converges to 0. Have you stated the question fully?
 

1. What is the significance of the "n^2" and "e^n" in the sequence?

The "n^2" represents the numerator of the sequence, which increases quadratically with each term. The "e^n" represents the denominator, which increases exponentially with each term. Together, they create a sequence that converges to 0 as n approaches infinity.

2. How can we determine the convergence of this sequence?

To determine the convergence of this sequence, we can use the ratio test or the root test. Both tests involve taking the limit of the ratio or root of consecutive terms in the sequence. If the limit is less than 1, the sequence converges. If the limit is greater than 1, the sequence diverges. If the limit is equal to 1, the test is inconclusive and another method must be used.

3. What is the limit of this sequence as n approaches infinity?

The limit of this sequence is 0 as n approaches infinity. This means that the sequence converges to 0, or "approaches" 0 as n gets larger and larger.

4. Can this sequence be used to solve real-world problems?

Yes, this sequence can be used to model real-world situations where the numerator increases quadratically and the denominator increases exponentially. For example, it can be used to model population growth, where the population (numerator) increases at a rate proportional to its current size, while the carrying capacity (denominator) limits the growth.

5. Are there any other types of sequences that converge to 0?

Yes, there are many types of sequences that converge to 0. Some common examples include geometric sequences with a common ratio less than 1, logarithmic sequences, and sequences involving factorials. It is important to use appropriate tests or methods to determine the convergence of each individual sequence.

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