Have to find three ways of solving (only have one successful)

  • Thread starter Thread starter Mabbott608
  • Start date Start date
Mabbott608
Messages
6
Reaction score
0

Homework Statement



x*y'' - y' = 3x^2


The Attempt at a Solution



so far i have used cauch-euler and solved it. i was trying to use linear de and power series to solve, but with little success. Am i on the right track? If not, which method should i be using to find the solution?
 
Physics news on Phys.org
Mabbott608 said:

Homework Statement



x*y'' - y' = 3x^2


The Attempt at a Solution



so far i have used cauch-euler and solved it. i was trying to use linear de and power series to solve, but with little success. Am i on the right track? If not, which method should i be using to find the solution?

I don't recall the Cauchy-Euler method is, so if that worked for you, great. Power series should work, so if you're having problems, show us what you've done.

You can also make the substitutiion u = y', u' = y'' to make the equation first order, and find an integrating factor. Once you have found u, integrate to get y.
 
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...
Back
Top