Solve the following initial value problem (DiracDelta function)

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SUMMARY

The initial value problem defined by the equation y'' + 4y = 2 delta(t - pi/4) with initial conditions y(0)=0 and y'(0)=0 is solved using the Laplace transform. The correct solution is y(t) = -Heaviside(t - pi/4)cos(2t), which accounts for the Dirac delta function's impact at t = pi/4. The initial attempt yielded an incorrect form involving a product of functions that cannot be inverse transformed directly.

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Homework Statement


y'' +4y = 2 delta(t - pi/4)

where y(0)=0 and y'(0)=0

Homework Equations


Laplace transform
Inverse Laplace transform


The Attempt at a Solution


after applying laplace tranform
Y(s)=2e^((-pi/4)*s) / s^(2)+4

as the final answer i have
y(t) = U(t-pi/4)*2sin(t-pi/4)

I'm not very comfortable with these types of problems yet, is my answer correct?
 
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I get the forward transform as:
[itex]s^2\tilde{y}(s) +4\tilde{y}(s) =2e^{-s\pi /4}[/itex]
Then isolating i get the same as you. But you got something wrong, the product of two functions can't be inverse transformed generally. The result should be:
[itex]-\text{Heaviside}(t-\pi/4)\cos(2t)[/itex]
 

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