(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

y'' + y = delta(t-2*pi)

3. The attempt at a solution

I have solved this using laplace transforms.

Y = e^(-2*pi*s)/(s^2 + 1) + 10s/(s^2 + 1)

so that

y = sint*u(t - 2*pi) + 10 *cost

what I don't understand is this function is not definied for t<0. According to my book, the answer is:

y = 10 cos t if 0<t<2*pi and y = 10cost + sint if t>2*pi

Why is this?

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# Homework Help: Differential equation using laplace transforms

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