Differential equations by series and also by an elementary method

Fachni
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Homework Statement



Solve the following differential equations by series and also by an elementary method and verify that your solutions agree.

(x^2+2x)y''-2(x+1)y'+2y=0

Homework Equations



y=\sum_{n=0}^{\infty} a_nx^n
y'=\sum_{n=1}^{\infty} na_nx^{n-1}
y''=\sum_{n=1}^{\infty} n(n+1)a_{n+1}x^{n-1}

The Attempt at a Solution



I have got a_1=a_0,\ a_3=0,\ a_4=-\frac{1}{8}a_3=0,\ a_5=-\frac{1}{5}a_4=0. Then, how do we find the recursive relation to find the solution?
 
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Isn't x=0 a singular point? You need to use the Frobenius method to get the series solution.

For the recursion relation, set the coefficient of xn to 0.
 
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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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