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# Differential Equations - Auxiliary Equation Method - Few Questions watch

1. 1) For the following D.E:

Now, I've got the Complimentary Function, in the form of:

Therefore, for the trial function of my Particular Integral, do I use:

or

Whichever I do use, when I differentiate my trial function (both times) and substitute my derivatives back into my original D.E, I tend to get two simultaneous equations but both in terms of m, l and t. Should I still have t in my equation? If so, do I try to eliminate it somehow, or keep my constants in terms of t?

2) Next D.E:

What would be my Particular Integral for this equation? Simply where c is a constant? It just I've never came across this kind of linear equation before and am not sure on what the trial function should be.

Thanks for any help, much appreciated.
2. X is always equal to 17. They don't want you to know that.
3. (Original post by bawlmorian)
X is always equal to 17. They don't want you to know that.
Ahhhhhhh I see it now.

All this time. I now know where I'm going wrong.

Oh wai-
4. 2) you need to guess a P.I of the form ax^2 + bx + c (ie if you're given a polynomial of degree n look for a forcing term of degree n).

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