- #1
VoteSaxon
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Homework Statement
Well I am looking for the particular integral of:
d2y/dt2 + 4y = 5sin2t
The attempt at a solution
As f(t) = 5sin2t, the particular integral yPI should look like:
yPI = Acos2t + Bsin2t
dyPI/dt = -2Asin2t + 2Bcos2t
d2yPI/dt2 = -4Acos2t - 4Bsin2t
Subbing into the differential equation, you get:
-4Acos2t - 4Bsin2t + 4(Acos2t + Bsin2t) = 5sin2t
cancelling ...
0 = 5sin2t
Surely this is incorrect. Any help please?
PS: I think I have already calculated the complementary function yCF, so to get the overall solution I need the particular integral, as yGEN = yCF + yPI
Edit: sorry for posting in the wrong forum, must have taken a wrong turn somewhere. Thanks for putting it right.
Well I am looking for the particular integral of:
d2y/dt2 + 4y = 5sin2t
The attempt at a solution
As f(t) = 5sin2t, the particular integral yPI should look like:
yPI = Acos2t + Bsin2t
dyPI/dt = -2Asin2t + 2Bcos2t
d2yPI/dt2 = -4Acos2t - 4Bsin2t
Subbing into the differential equation, you get:
-4Acos2t - 4Bsin2t + 4(Acos2t + Bsin2t) = 5sin2t
cancelling ...
0 = 5sin2t
Surely this is incorrect. Any help please?
PS: I think I have already calculated the complementary function yCF, so to get the overall solution I need the particular integral, as yGEN = yCF + yPI
Edit: sorry for posting in the wrong forum, must have taken a wrong turn somewhere. Thanks for putting it right.
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