Value of laplace transform for the time-domain signal equation

Q.  What should be the value of laplace transform for the time-domain signal equation e-at cos ωt.u(t)?
- Published on 30 Nov 15

a. 1 / s + a with ROC σ > - a
b. ω / (s + a) 2 + ω2 with ROC σ > - a
c. s + a / (s + a)2 + ω2 with ROC σ > - a
d. Aω / s2 + ω2 with ROC σ > 0

ANSWER: s + a / (s + a)2 + ω2 with ROC σ > - a
 

    Discussion

  • jakkoju hemasri   -Posted on 24 Oct 16
    like the question and ans
  • rupesh   -Posted on 12 Aug 16
    We know,
    L.T of cos wt= s/(s2)+w2
    And for e^at=1/(s+a).
    Therefore L.T of e^-at coswt=(s+a)/(s+a)2 +w2
    Here instead of s we add (s+a)..
  • birendra kumar pal   -Posted on 03 Jul 16
    i like this q and ans

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