Form of a particular solution for N.H.L.D.E. w/ constant coefficients

jegues
Messages
1,085
Reaction score
3

Homework Statement



You are given that the roots of the auxiliary equation associated with the linear, differential equation

\phi(D)y = 2x- 3xe^{-3x}

are m = \pm2,0,0. Write down the form of a particular solution of the differential equation as predicted by the method of undetermined coefficients. Do NOT find the coefficients, just the form of the particular solution.

Homework Equations





The Attempt at a Solution



See figure attached for my attempt at the solution. I'm not entirely convinced I'm doing this properly so I'd just like for someone to verify my work.

Thanks again!
 

Attachments

  • 08Q6.jpg
    08Q6.jpg
    18.4 KB · Views: 406
Physics news on Phys.org
Not sure what the various rules you refer to are, but the answer and reasoning look right to me.
 
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