I am looking for the annihilator of $e^x\cos3x$.
I know that for $\cos(\alpha x)+\sin(\alpha x)$ the annihilator is $(D+\alpha)^2$ as the solutions have to be $-\alpha i$ and $\alpha i$ but what if the function is just $\cos$ or $\sin$?
Annihilator for the function $e^x\cos3x$
0
$\begingroup$
ordinary-differential-equations
-
0Try $(D-1)^2+9$ – 2017-02-05
-
0@s.harp if it was just $cos 3x$ is would have been $D^2+9$? doesnt it given $cos3x+sin3x$? – 2017-02-05