why does the general solution to the euler-cauchy equation only work for x>0?
It doesn't. It may well work for x< 0. Certainly, because the general equation has a singularity at x= 0, we can't expect a general solution to exist at x= 0 or be extended past x= 0- but you can have solutions that are valid for x> 0 and solutions that are valid for x< 0.
ok, that makes sense~ :)
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