Show that the Gamma function is converging

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SUMMARY

The discussion focuses on the convergence of the gamma function, defined as \(\Gamma(n) = \int_0^{\infty} t^{n-1} e^{-t} dt\) for \(n \geq 1\). The user successfully demonstrated the convergence using the comparison test after initially attempting integration by parts. Additionally, the user confirmed the recursive property \(\Gamma(n+1) = n \Gamma(n)\) and the relationship \(\Gamma(n+1) = n!\) for integer values of \(n \geq 1\).

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Homework Statement



The gamma function, which plays an important role in advanced applications, is defined for

n\geq1 by \Gamma(n)=\int_0^{\infty} t^{n-1}e^{-t}dt

(a) Show that the integral converges on n\geq1

(b) Show that \Gamma(n+1)=n\Gamma(n)

(c) Show that \Gamma(n+1)=n! if n\geq1 is an integer

The Attempt at a Solution



I am only having trouble with part (a)

(a) I used integration by parts to get

e^{-t}nt^{n}+\int_0^{\infty} t^{n}e^{-t}dt

I also tried it with a different u and dv:

-t^{n-1}e^{-t}+(n-1)\int_0^{\infty} t^{n-2}e^{-t}dt

I used this second IBP to find part (b), which I used for (c).

How can I show it is converging?
 
Last edited:
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Never mind, I figured it out with a comparison test.
Funny, after I post things on here I always seem to figure them out on my own.
Well, whatever works!
 

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