## anonymous 3 years ago Having trouble with the particular solution: y''+4y'+8y=2cos(2t)+sin(2t)

1. anonymous

Guess Acos(2t)+Bsin(2t)

2. anonymous

I tried $y_p=A \cos 2t+B \sin 2t$ and plugged in its derivatives, but I ended up with A=2/13 and B=3/13, but in the answer they are A=0 and B=1/4

3. anonymous

Oops I the 2 in 2t when differentiating. That's probably it, gonna try it now.

4. anonymous

I neglected* the 2 in 2t