Find lim (x^2n - 1)/(x^2n + 1) x->infinity->

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In summary, the limit of (x^2n - 1)/(x^2n + 1) as x tends to infinity can be rewritten as (B - 1)/(B + 1) for some large B. For real numbers, the limit is equal to 1 if x > 1, -1/2 if x = 1, -1 if 0<=x<1, and is undefined if x<0. For complex numbers with non-zero imaginary part, the limit is equal to -1 if |x| < 1 and is undefined if |x| >= 1. When n tends to infinity, the limit is equal to one if |x| > 1, 0 if
  • #1
lizzie
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find lim (x^2n - 1)/(x^2n + 1)
x->infinity
-> means tends to
 
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  • #2


lizzie said:
find lim (x^2n - 1)/(x^2n + 1)
x->infinity
-> means tends to

Have you tried substituting x=1/h so as x->infinity, h->zero.
Using this I got the answer as 1
 
  • #3


This is just (B - 1)/(B + 1) for some B that gets really big (goes to infinity with x). For all problems of this form you can just divide out the B and you'll see that the little stuff like +1 and -1 drop out.
 
  • #4


lizzie said:
find lim (x^2n - 1)/(x^2n + 1)
x->infinity
-> means tends to

Off the top of my head, my best guess is ...

For real numbers, the limit is equal to 1 if x > 1, -1/2 if x = 1, -1 if 0<=x<1, and is undefined if x<0.

For complex numbers with non-zero imaginary part, the limit is equal to -1 if |x| < 1 and is undefined if |x| >= 1.
 
  • #5


what will happen if n-> infinity
 
  • #6


You asked that originally and you have already been given 4 answers.
 
  • #7


DeaconJohn said:
Off the top of my head, my best guess is ...

For real numbers, the limit is equal to 1 if x > 1, -1/2 if x = 1, -1 if 0<=x<1, and is undefined if x<0.

For complex numbers with non-zero imaginary part, the limit is equal to -1 if |x| < 1 and is undefined if |x| >= 1.

HallsofIvy said:
You asked that originally and you have already been given 4 answers.

The original question asked for x--> infinity, not n.

As for the original question- Try adding and then subtracting 2 off the numerator.

For when n --> infinity, DJ had an attempt but needs some corrections: the limit is equal to one if |x| > 1, 0 if |x|=1, -1 if |x| < 1 and not undefined for any values. Note that we have an even function, so none of the "undefined if x<0" stuff.
 
Last edited:
  • #8


Gib Z said:
The original question asked for x--> infinity, not n.

As for the original question- Try adding and then subtracting 2 off the numerator.

For when n --> infinity, DJ had an attempt but needs some corrections: the limit is equal to one if |x| > 1, 0 if |x|=1, -1 if |x| < 1 and not undefined for any values. Note that we have an even function, so none of the "undefined if x<0" stuff.

Gib Z, You are absolutely correct. My answer is in the context of n --> infinity. Funny thing is that I thought I was addressing the question of when x --> infinity. A credit to your understanding to realize that my calculations assumed n --> infinity. Unfortunately, I don't have anything to say about the case when x --> infinity, and the time that I've alloted to spend on this interesting problem of yours has expired.

I think I'll probably be concentrating on the number theory board in the future. That is the area of math that interests me most these days. It is also the area I know least about.

DJ
 

FAQ: Find lim (x^2n - 1)/(x^2n + 1) x->infinity->

What is the limit of the function (x^2n - 1)/(x^2n + 1) as x approaches infinity?

The limit of the function (x^2n - 1)/(x^2n + 1) as x approaches infinity is 1. As x gets larger and larger, the terms with higher exponents (x^2n) become insignificant compared to 1. Therefore, we can simplify the function to 1/1, which equals 1.

How do you prove the limit of the function (x^2n - 1)/(x^2n + 1) as x approaches infinity is 1?

We can prove this limit by using the definition of a limit. Let L be the limit of the function as x approaches infinity. Then, for any positive number e, there exists a corresponding positive number N such that for all x greater than N, the absolute value of (x^2n - 1)/(x^2n + 1) - L is less than e. By simplifying the function to 1/1 and setting N to a large enough value, we can show that this condition is met, and therefore, the limit is 1.

Is the limit of the function (x^2n - 1)/(x^2n + 1) as x approaches infinity always 1?

Yes, the limit of the function (x^2n - 1)/(x^2n + 1) as x approaches infinity is always 1. This is because, as mentioned in the first answer, the terms with higher exponents become insignificant compared to 1 as x gets larger and larger. Therefore, the limit is always 1.

Can the limit of the function (x^2n - 1)/(x^2n + 1) as x approaches infinity be negative?

No, the limit of the function (x^2n - 1)/(x^2n + 1) as x approaches infinity cannot be negative. Since the terms with higher exponents become insignificant compared to 1, the numerator will always be 1 or a positive number, while the denominator will always be a positive number. Therefore, the limit will always be a positive number, and cannot be negative.

How does the value of n affect the limit of the function (x^2n - 1)/(x^2n + 1) as x approaches infinity?

The value of n does not affect the limit of the function (x^2n - 1)/(x^2n + 1) as x approaches infinity. As n increases, the terms with higher exponents become even more insignificant compared to 1, but the overall limit remains 1. This is because, no matter the value of n, the function can always be simplified to 1/1, which equals 1.

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