Solving Limit Problem: n→∞, n!-1/n³ln(n!)

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In summary, the conversation discusses the limit of a certain equation as n approaches infinity and how it can be demonstrated for all integers m > 0. The conversation also discusses the importance of observing what happens as n tends to infinity in order to understand the limit better.
  • #1
Lisa91
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Could anyone tell me please why the limit of this guy is infinity?

[tex] \lim_{n\to\infty} \frac{n!-1}{n^{3} \ln(n!)} [/tex]
 
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  • #2
Lisa91 said:
Could anyone tell me please why the limit of this guy is infinit
[tex] \lim_{n\to\infty} \frac{n!-1}{n^{3} \ln(n!)} [/tex]
See what you can do with this inequality.

$\ln \left( {n!} \right) = \sum\limits_{k = 1}^n {\ln (k)} \leqslant \sum\limits_{k = 1}^n k =\frac{{n(n + 1)}}{2}$
 
  • #3
The 'core' of the problem is to demonstrate that...

$\displaystyle \lim_{n \rightarrow \infty} \frac{n!}{n^{m}} = \infty$ (1)

... for all integers m>0. That is easily achieved supposing n>m, writing ...

$\displaystyle \frac{n!}{n^{m}}= \frac{n\ (n-1)\ (n-2)\ ...\ (n-m+1)}{n^{m}}\ (n-m)\ (n-m-1)\ ...\ 2 = $

$\displaystyle = 1\ (1- \frac{1}{n})\ (1-\frac{2}{n})\ ... (1-\frac{m-1}{n})\ (n-m)\ (n-m-1)\ ...\ 2$ (1)

... and observing what happens if n tends to infinity...

Kind regards$\chi$ $\sigma$
 

Related to Solving Limit Problem: n→∞, n!-1/n³ln(n!)

1. What is a limit problem?

A limit problem is a mathematical concept that involves finding the value that a function approaches as its input approaches a certain value, typically infinity or negative infinity. In other words, it is finding the "limit" of a function as it gets closer and closer to a specific point.

2. What is n!?

n! (pronounced "n factorial") is a mathematical notation that represents the product of all positive integers from 1 up to and including n. For example, 5! = 1 x 2 x 3 x 4 x 5 = 120.

3. How do you solve a limit problem with n! in the equation?

When solving a limit problem with n! in the equation, you can use the formula n! = n x (n-1) x (n-2) x ... x 2 x 1 to simplify the expression. Then, you can use algebraic manipulation and known limit rules to evaluate the limit.

4. Why is the expression n!-1/n³ln(n!) used in limit problems?

This expression is often used in limit problems because it involves a factorial and a natural logarithm, both of which can be challenging to evaluate. It also allows for the use of various limit rules and techniques to solve the problem.

5. How does the limit of n→∞, n!-1/n³ln(n!) behave?

As n approaches infinity, the expression n!-1/n³ln(n!) also approaches infinity. This is because the factorial term grows much faster than the natural logarithm term, resulting in an infinitely large value.

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