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Signals and systems electrical engineering miscellaneous

  1. Consider an LTI system with impulse response h(t) = e–5t u(t). If the output of the system is y(t) = e–3t u(t) then the input, x(t), is given by
    1. e–3t u(t)
    2. 2–3t u(t)
    3. e–5t u(t)
    4. 2–5t u(t)
Correct Option: B

h(t) = e–5t u(t)
Laplace transform gives,

H(s) =
1
s + 5

y(t) = e–3t u(t) – e–5t u(t)
Laplace transform gives,
Y(s) =
1
-
1
=
2
s + 3s + 5(s + 3)(s + 5)

Then, X(s) =
Y(s)
=
2(s + 5)
=
2
H(s)(s + 3)(s + 5)s + 3

Inverse Laplace transform gives,
x(t) = L–1 X (s) = 2e–3t u(t)



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