How to Modify Y(t) for Nonhomogenous 2nd Order DE with e^-t and cos(2t) Terms?

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SUMMARY

The discussion focuses on modifying the particular solution Y(t) for the nonhomogeneous second-order differential equation y'' + 2y' + 5y = 4e^{-t}cos(2t). The initial attempt using Y(t) = Ae^{-t}cos(2t) + Be^{-t}sin(2t) resulted in zero, indicating the need for modification. The recommended approach is to use Y(t) = Ae^{-t}tcos(2t) + Be^{-t}tsin(2t), which accounts for the resonance caused by the homogeneous solution, thus providing a valid particular solution.

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Homework Statement


Well I've got another one that totally sucks.
y'' + 2y' + 5y = 4e^{-t}cos(2t)

Homework Equations


The Attempt at a Solution



I tried Y(t) = Ae^{-t}cos(2t) + Be^{-t}sin(2t) but that unfortunately yielded 0 = 4e^{-t} cos(2t)

So my question is how does one modify Y(t) in this type of situation? The only thing I can think of is something like Y(t) = Ae^{-t}t^2cos(2t) + Be^{-t}tsin(2t) but that seems rather painful
 
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Try,
<br /> Y(t) = Ae^{-t}tcos(2t) + Be^{-t}tsin(2t)<br />
which is what you wrote down but I changed a t^2 to a t. Yeah, it's kind of painful, but it will work. Without the t's it just the homogeneous solution. You knew that would give you zero, right?
 
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