## yaro99 2 years ago Steady state solution 4y''+12y'+9y=225-75sin(3t) I'm not sure what to do about the 225, I'd be able to solve it if it was just the sine term on the right.

1. TuringTest

Just add another constant in your guess for the particular if you are using undefined variables.

2. yaro99

So it would be in the form $K+a*\cos(3t)+b*\sin(3t)$?

3. TuringTest

right

4. yaro99

Cool, I got the solution. Thanks!

5. TuringTest

welcome :D