The equation you've provided is:

$y = e^{-x}(c_1 \cos 3x + c_2 \sin 3x)$

To eliminate the arbitrary constants $c_1$ and $c_2$, you typically need boundary conditions (like values of $y$ and its derivatives at specific points). Without specific boundary conditions, we can rewrite the general solution in terms of known forms, but eliminating arbitrary constants completely would require additional information.

Could you provide any conditions or additional details? If so, I can help with finding a particular solution and removing those constants.