(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

y''' + y'' - 6y' = 36x

2. Relevant equations

y'' + y' - 6y =18x^2

3. The attempt at a solution

I've integrated the third order D.E. to get a second order D.E.

Solving the characteristic equation, to find a general solution, I get:

y = c_1exp(-3x) + c_2exp(2x)

However, the answer is given as c_1 + c_2exp(-3x) + c_3exp(2x).

Where is the extra term coming from?

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# Homework Help: D.E.s Undetermined Coefficients

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