Integration by Parts of <C> i just cannot do

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SUMMARY

The discussion focuses on the integration by parts of the integral I'_{1}(\alpha) = ∫_{0}^{+\infty} C e^{-\alpha C^{2}} dC, which evaluates to 1/(2α). The subsequent integral I'_{3}(\alpha) = ∫_{0}^{+\infty} C^{3} e^{-\alpha C^{2}} dC is derived by differentiating I'_{1} with respect to α, resulting in 1/(2α²). A correction was noted regarding the inclusion of π in the denominator of the final answer.

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Rachael_Victoria
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Can anyone outline, and this is a rather large request, the step by step integration by parts for <C>? This is not a homework question but more something i need to be able to do on tuesday for my final, and have been trying to do for two days.
 

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Your answer is incorrect.

Here's how it's done.

Knowing this integral's value

[tex]I'_{1}(\alpha)=:\int_{0}^{+\infty} C e^{-\alpha C^{2}} \ dC =\frac{1}{2\alpha}[/tex] (1)

,one sees immediately that

[tex]I'_{3}(\alpha)=:\int_{0}^{+\infty} C^{3} e^{-\alpha C^{2}} \ dC=-\frac{d}{d\alpha}I'_{1}=\frac{1}{2\alpha^{2}}[/tex] (2)

and now plug in (2) the expression for '\alpha'.

Daniel.
 
Thank you, and you're right, i forgot to type the pi in the denominator for the answer.
 

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