Solution of the radial part of the laplace-equation

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SUMMARY

The radial part of the Laplace equation is expressed as r²(d²/dr²)U(r) = l(l+1)U(r). The correct solution to this equation is U(r) = a_l*r^l + b_l/r^(l+1), not U(r) = a_r*r^l + b_l/r^l as initially proposed. The error in the original expression was identified as using l(l-1) instead of l(l+1). For accurate solutions, refer to the proper formulation of Laplace's equation in spherical coordinates.

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Homework Statement


I got the the radial part of the Laplace-Equation:

r^2(\frac{d^2}{dr^2}U(r))=l(l+1)U(r)

Now I should show that the following solves the equation:

a_l*r^l+\frac{b_l}{r^l}

The Attempt at a Solution


29.11.1222-05-30rfq7k.jpg

The problem is that I got l(l-1) instead of l(l+1) :(
 
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Hello, and welcome to PF!
Faust90 said:

Homework Statement


I got the the radial part of the Laplace-Equation:

r^2(\frac{d^2}{dr^2}U(r))=l(l+1)U(r)

The expression on the left is incorrect. See http://physicspages.com/2012/01/20/laplaces-equation-spherical-coordinates/ for Laplace's equation in spherical coordinates.
 
Sorry for the late answer. the ansatz was wrong, instead of a_r*r^l+\frac{b_l}{r^l} it has to be:

a_r*r^l+\frac{b_l}{r^{l+1}}
 

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