Solve Dirac Delta Function IVP: y''-2y'-3y=2\delta (t-1)-\delta (t-3)

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SUMMARY

The discussion focuses on solving the initial value problem (IVP) represented by the equation y'' - 2y' - 3y = 2δ(t-1) - δ(t-3) with initial conditions y(0) = 2 and y'(0) = 2. The solution involves applying the Laplace transform, leading to the expression Y(s) = (2e^{-s} - e^{-3s} + 2s - 2) / (s² - 2s - 3). The final solution is presented as y(t) = e^{1-t}(e^{4t-4}-1)u(t-1) - 2e^{3-t}(e^{4t-12}-1)u(t-3) + e^{-t} + e^{3t), confirming the correctness of the approach taken.

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Homework Statement
Solve the given symbolic initial value problem: y''-2y'-3y=2\delta (t-1)-\delta (t-3) ;y(0)=2,y'(0)=2


The attempt at a solution

Let Y(s):= L{y(t)}(s)

Taking laplace transform of both sides:


[s^{2}Y(s)-2s-2]-2[sY(s)-2]-3Y(s)=2e^{-s}-e^{-3s}
s^{2}Y(s)-2sY(s)-3Y(s)=2e^{-s}-e^{-3s}+2s-2
Y(s)=\frac{2e^{-s}-e^{-3s}+2s-2}{s^{2}-2s-3}
Y(s)=\frac{2e^{-s}}{s^{2}-2s-3}- \frac{e^{-3s}}{s^{2}-2s-3}+\frac{2s-2}{s^{2}-2s-3}
y(t)=e^{-(t-1)}\frac{1}{2}e^{-(t-1)}(e^{4(t-1)}-1)u(t-1)-e^{-(t-3)}e^{-(t-3)}(e^{4(t-3)}-1)u(t-3)+e^{-t}+e^{3t}

And my final answer:


y(t)=e^{1-t}(e^{4t-4}-1)u(t-1)-2e^{3-t}(e^{4t-12}-1)u(t-3)+e^{-t}+e^{3t}

Is this correct?
 
Physics news on Phys.org
It looks to be right sort of thing to be doing.
 

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