Is the Limit of x^n/e^x Equal to 0 for Negative Integers?

  • Thread starter phymatter
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In summary, using L'Hopital's rule for any fixed n, the result will always be 0 for x^n/e^x with n being negative. This is because both x^n and e^x grow without bound as x goes to infinity, resulting in a fraction that approaches 0. Additionally, the limit of (->infinity)0 is not well-defined and could be either 0 or 1 depending on the actual function and limit being evaluated.
  • #1
phymatter
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is limx->infinity xn/ex =0 for n = -ve integers , if yes then why?
also is (->infinity)0 =1 ?
 
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  • #2


You know if you get inifinity over infinity you must "change" your fractionexpression by using L'hopitas rule. It says that if you either get infinity over ifinity or zero over zero you must derive nominator og denominator so that you get a fractionexpression which is capable of giving you an answer by substituting the variable x.
 
  • #3


phymatter said:
is limx->infinity xn/ex =0 for n = -ve integers , if yes then why?
also is (->infinity)0 =1 ?

I don't know what you mean by n = -ve integers. However using L'Hopital's rule for any fixed n, the result will always be 0. ex will persist as you take derivatives, while xn will be 0 after n derivatives.
 
  • #4


mathman said:
I don't know what you mean by n = -ve integers.
by n = -ve integers i mean that n={-1,-2,-3,-4,...}
 
  • #5


phymatter said:
is limx->infinity xn/ex =0 for n = -ve integers , if yes then why?
also is (->infinity)0 =1 ?
Surely it is not that difficult to write "negative"!

In any case, it should be obvious that x^n/e^x, for n negative, is the same as 1/(x^ne^x) with n positive. And since both x^n and e^x grow without bound as x goes to infinity, the fraction goes to 0.

Again (->infinity) makes no sense. If you mean [itex]\lim_{x\to\infty}f(x)[/itex] it still makes no sense because that limit might be 0, in which case [itex]0^0[/itex] is not defined, or that limit might be a non-zero number, in which case the limit is 1.
 

1. What does "Limx->infinity xn/ex =0" mean?

The notation "Limx->infinity xn/ex =0" is read as "The limit of xn divided by ex as x approaches infinity is equal to 0". It is a mathematical statement used to describe the behavior of a function as the input approaches a very large value (infinity).

2. Why is the limit of xn/ex equal to 0 as x approaches infinity?

This is because, as x approaches infinity, the exponential function ex grows much faster than the polynomial function xn. Therefore, the fraction xn/ex becomes smaller and smaller, eventually approaching 0 as x gets larger and larger.

3. Is it possible for the limit of xn/ex to be a value other than 0?

Yes, it is possible. The limit of xn/ex can be any value other than 0 if the degree of the polynomial xn is greater than or equal to the degree of the exponential function ex. In this case, the exponential function grows slower than the polynomial function, causing the limit to be a non-zero value.

4. How is the limit of xn/ex related to the growth rate of the functions xn and ex?

The limit of xn/ex can be used to determine the growth rate of xn and ex. If the limit is 0, it means that the exponential function ex grows faster than the polynomial function xn. If the limit is a non-zero value, it means that the polynomial function xn grows faster than the exponential function ex.

5. What are some real-world applications of understanding the limit of xn/ex as x approaches infinity?

The concept of limits is fundamental in calculus and is used to model various real-world phenomena, such as population growth, radioactive decay, and financial investments. Understanding the limit of xn/ex as x approaches infinity can help in predicting the behavior of these phenomena and making informed decisions.

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