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

Find the appropiate particular solution form for

y''' - y'' - 12y' = x - 2x*e^-(3x)

DO NOT SOLVE FOR THE COEFFICIENTS

2. Relevant equations

Just guessing proper solution forms for nonhomogeneous second order D.Es with undetermined coefficients.

3. The attempt at a solution

Ok, as far as I know the solution in my mind was...

Ax + B + (Cx^2 + Dx) e ^(-3x)

The homogeneous solution was yc = c1 + c2e^(4x) + c3e^(-3x)

BUT

the solution is Ax + Bx^2 + (Cx + Dx^2)e^(-3x)

I don;t know why the B has x^2, and I don't know why D and C are switched around. I've been going at this for a good hour.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Find the appropriate particular solution.

**Physics Forums | Science Articles, Homework Help, Discussion**