Mastering the Integration of 1/sqrt(x-1): Tips and Tricks

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In summary, The conversation discusses different substitution options for solving an improper integral of 1/sqrt(x-1). The first suggestion is u^{2} = x-1, followed by a suggestion for a simpler substitution of u=x+1. However, upon trying both options, it is revealed that u=x-1 is the better choice and results in an easy solution.
  • #1
eddysd
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Trying to do an improper integral but for some reason am flummoxed by the integration of 1/sqrt(x-1).
 
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  • #2
Have you tried the substitution [tex]u^{2} = x-1 [/tex]?
 
  • #3
nope, thank-you!
 
  • #4
Why that substitution, I wonder? It seems to me that the substitution u=x+1 would be simpler... but I'm sure that, if I tried yours, it would work out just as easy.

Wait, I did. And it was quite easy. Thanks for the alternative substitution route, I actually like this one better.
 
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  • #5
╔(σ_σ)╝ said:
Have you tried the substitution [tex]u^{2} = x-1 [/tex]?

Char. Limit said:
Why that substitution, I wonder? It seems to me that the substitution u=x+1 would be simpler... but I'm sure that, if I tried yours, it would work out just as easy.

Wait, I did. And it was quite easy. Thanks for the alternative substitution route, I actually like this one better.

Probably a typo, but u = x - 1 is a better choice than u = x + 1.
 
  • #6
Mark44 said:
Probably a typo, but u = x - 1 is a better choice than u = x + 1.

Indeed. u=x-1 is what I meant.
 

1. What is the domain and range of the function?

The domain of 1/sqrt(x-1) is x > 1, since the function is undefined for x = 1. The range is all real numbers greater than or equal to 0, since the square root of any number can never be negative.

2. How do I solve the integral of 1/sqrt(x-1)?

To solve the integral of 1/sqrt(x-1), you can use the substitution method. Let u = sqrt(x-1), then du/dx = 1/(2*sqrt(x-1)). This means that dx = 2*sqrt(x-1)*du, which you can then substitute into the integral. This will result in the integral becoming the more manageable form of ∫1/u du, which can be easily solved using the power rule.

3. Is there a shortcut or trick to solving this integral?

Yes, there is a shortcut called the trigonometric substitution method. You can let x = sec^2(theta), which will result in dx = 2tan(theta)*sec(theta)d(theta). This substitution will transform the integral into ∫1/tan(theta)sec(theta)d(theta), which can be solved using the double angle formula for tangent.

4. How do I use the answer to this integral in real-world applications?

The integral of 1/sqrt(x-1) can be used in real-world applications involving rates of change. For example, it can be used to calculate the velocity of an object moving along a curved path with a varying radius of curvature, or to calculate the rate of change of temperature in a system with a varying heat transfer coefficient.

5. Is there a graph of this function available?

Yes, the graph of 1/sqrt(x-1) can be easily plotted using various online graphing tools or software. It will show a curve that approaches infinity as x approaches 1 from the right, and gradually decreases as x increases. The graph will also show a vertical asymptote at x = 1.

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