Integration problem : Beta function related

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Homework Help Overview

The problem involves evaluating an integral related to the beta function, specifically in a context where the limits of integration are not standard. The original poster expresses difficulty in transforming the integral to fit the beta function's requirements.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to use a substitution to transform the integral into a form suitable for the beta function but encounters issues with the resulting expression. Some participants suggest a straightforward u-substitution as an alternative method, while others note the integral's relation to the incomplete beta function.

Discussion Status

The discussion includes various approaches to the problem, with some participants providing alternative methods and others acknowledging the original poster's concerns about fitting the integral into the beta function framework. There is no explicit consensus on a single solution, but helpful guidance has been shared.

Contextual Notes

The original integral's limits and form are under scrutiny, as they deviate from the standard beta function setup. The discussion reflects on the implications of these constraints and the potential for using the incomplete beta function.

Alhussein
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Homework Statement



the problem is in the figure

Homework Equations



beta function = ∫u^x-1 * (1-u)^y-1 du " the integral is form 0 to 1"

The Attempt at a Solution



to use the beta function the integral must be from 0 to 1 but this problem is from 0 to a
so i let X^2=a^2 * t
and i got from it x, dx . the integral became from 0 to 1 and everything seemed fine till i found that the (1-x)^0.5 will be (1-a root t)^0.5 which isn't the general forum of the beta function. so i hope any1 will help me or tell me if there's another way to solve this integral without the beta function if it's possible
 

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You could just do the u-substitution u=1-x. So just expand x^4=(1-u)^4 and integrate term by term.
 
Dick said:
You could just do the u-substitution u=1-x. So just expand x^4=(1-u)^4 and integrate term by term.


hmm ty for this answer it worked out well.but don't u know any solution for it by using beta function since the problem in the book was after that lesson
 
Alhussein said:
hmm ty for this answer it worked out well.but don't u know any solution for it by using beta function since the problem in the book was after that lesson

Well, your original integral is an 'incomplete beta function' if that's what your are after.
 
Dick said:
Well, your original integral is an 'incomplete beta function' if that's what your are after.

yea i figured that after awhile. anyway thanks a lot for your help
 

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