Strange way of solving a linear 2nd order DE

Alexrey
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Homework Statement


I was given a DE of the form: \Phi^{''}+(6/\eta)\Phi^{'}=0 where the next step was given as \Phi^{'} \propto \eta^{-6} where the answer came out to be \Phi \propto \eta^{-5} + constant

The Attempt at a Solution


My attempt was to set \Phi^{'}=x where I would then get x^{'}=-(6/\eta)x and then solve for a seperable DE, but my answer was incorrect. Any help would be appreciated, thanks guys.

Any help would be appreciated, thanks guys.
 
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Alexrey said:
x^{'}=-(6/\eta)x
To clarify, η is the independent variable, and differentiation is wrt that? If so dx/x=-6d\eta/\eta yes? Isn't it straightforward from there?
 
About 5 minutes after posting this I figured it out. :/ Thanks for replying though, I appreciate it, that's exactly what I got. Cheers!
 
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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