Integrating Legendre Polynomials Pl & Pm

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Homework Statement


Integrate the expression
Pl and Pm are Legendre polynomials

Homework Equations






The Attempt at a Solution


Suppose that solution is equal to zero.
 

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What properties do you know about Legendre Polynomials? If you can use the orthogonal properties that are listed in the article on Legendre polynomials in wikipedia, then integration by parts should do the trick.
 
TheFurryGoat said:
What properties do you know about Legendre Polynomials? If you can use the orthogonal properties that are listed in the article on Legendre polynomials in wikipedia, then integration by parts should do the trick.

But, how make Pm'(x) I don't understand(recurrent differentiation formula?)
 
Under the orthogonality section in the wikipedia article on Legendre polynomials, you find the identity
\displaystyle \frac{d}{dx}\left[(1-x^2)\frac{d}{dx}P(x)\right] = -\lambda P(x)
where the eigenvalue \lambda corresponds to n(n+1).
I suppose P(x)=P_n(x) for any n, but I'm not sure though. If this is the case, and you know this property, then integration by parts should do the trick.
 
Thanks for help, I succeeded to do job.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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