Differential equations - finding constants

shinobiazra
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Find values of the constants a and k so that y(x) = ax^k solves the differential equation;

(dy/dx)^2 + [(3y^2)/(x^2)] + [(2y)/(x^4)]


I tried substituiting ax^k into the DE but it did not work. I need to separate x and y but I cannot do it then I need to integrate it I think. I just don't know how to go about this question.

HELP!
 
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I see no equation, only an expression. I guess you mean that this expression equals zero?

Please show what you've done so far with substitution
 
Hi shinobiazra! :smile:

(try using the X2 tag just above the Reply box :wink:)
shinobiazra said:
I tried substituiting ax^k into the DE but it did not work. I need to separate x and y but I cannot do it then I need to integrate it I think.

No, there's no integration, all you need to do is differentiate.

If y = axk, what is dy/dx? :smile:
 
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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