Limit of arccosh x - ln x as x -> infinity

In summary, the problem asks to find the limit of arccoshx - ln x as x approaches infinity. Using the equation arccosh x = ln (x + sqrt(x^2-1)), the limit can be rewritten as the limit of ln ((x + sqrt(x^2-1))/x). Simplifying further, the limit becomes ln (1 + sqrt(1-1/x^2)). By manipulating the expression, it can be shown that the limit of this expression is 1, thus the limit of arccoshx - ln x as x approaches infinity is 1.
  • #1
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Homework Statement


find the limit of arccoshx - ln x as x -> infinity

Homework Equations


##arccosh x = \ln (x +\sqrt[]{x^2-1} )##

The Attempt at a Solution


## \lim_{x \to \infty }(\ln (x + \sqrt{x^2-1} ) - \ln (x)) = \lim_{x \to \infty} \ln (\frac{x+\sqrt{x^2-1}}{x})

\ln (1 + \lim_{x \to \infty}\frac{\sqrt{x^2-1}}{x})##

I can see that the limit of the second part is also going to one, but I can't manipulate the expression to show this.
 
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  • #2
I think it is ##\lim_{x\rightarrow +\infty} \ln{(x+\sqrt{x^{2}-1})}-\ln{x}=\lim_{x\rightarrow +\infty} \ln{\frac{x+\sqrt{x^{2}-1}}{x}}## that is ##\lim_{x\rightarrow +\infty} \ln{\left(1+\sqrt{1-\frac{1}{x^{2}}}\right)}##
 
  • #3
I was just about to come here and say "Wow I'm really stupid, I got it now". But you'd already answered. Thanks :D.
 
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Related to Limit of arccosh x - ln x as x -> infinity

1. What is the limit of arccosh x - ln x as x approaches infinity?

The limit of arccosh x - ln x as x approaches infinity is equal to infinity. This means that as x gets larger and larger, the value of the expression also gets larger and larger without bound.

2. How do you find the limit of arccosh x - ln x as x approaches infinity?

To find the limit of arccosh x - ln x as x approaches infinity, we can use the properties of limits and the fact that arccosh x and ln x are both continuous functions. We can rewrite the expression as ln(e^arccosh x) - ln x, and then use the property that the log of a product is equal to the sum of the logs. This simplifies the expression to ln(e^arccosh x / x), and as x approaches infinity, the numerator approaches infinity and the denominator approaches infinity, resulting in a limit of infinity.

3. Is the limit of arccosh x - ln x as x approaches infinity equal to the limit of ln x as x approaches infinity?

No, the limit of arccosh x - ln x as x approaches infinity is not equal to the limit of ln x as x approaches infinity. This is because the arccosh x function grows at a much faster rate than the ln x function as x approaches infinity, resulting in a limit of infinity for arccosh x - ln x while the limit of ln x remains at infinity.

4. Can the limit of arccosh x - ln x as x approaches infinity be negative?

No, the limit of arccosh x - ln x as x approaches infinity cannot be negative. This is because both arccosh x and ln x are positive functions, and as x approaches infinity, the difference between them will always result in a positive value, approaching infinity.

5. Is there a specific method for evaluating the limit of arccosh x - ln x as x approaches infinity?

Yes, there is a specific method for evaluating the limit of arccosh x - ln x as x approaches infinity. This involves using the properties of limits and the fact that both arccosh x and ln x are continuous functions. By rewriting the expression and using the properties of logs, we can simplify the expression and evaluate the limit as x approaches infinity. This method can be applied to other limits involving transcendental functions as well.

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