1. The problem statement, all variables and given/known data The problem: y''' + 8y = 2x - 5 + 8 e^(-2x); y(0) = -5, y'(0) = 3, y''(0) = -4 Correct answer: y = -23/12 e^(-2x) + e^x (-59/24 cos(sqrt(3) x) + 17 sqrt(3)/72 sin(sqrt(3) x)) + 1/4 x - 5/8 + 2/3 x e^(-2x) 2. Relevant equations Method of undetermined coefficients. 3. The attempt at a solution My work is attached as the TheProblemAndMyWork.pdf file. The work is typed (not handwritten), so it looks nice. What I'm having trouble with is finding the values for c_1, c_2 and c_3. I entered the system of equations from my work into Wolfram Alpha, and the answer is wrong! I re-did this problem so many times, and I keep ending up in the same situation. I suppose, I keep making the exact same mistake. Could someone please tell me what I am doing wrong? Any help would be GREATLY appreciated!