Laplace Transform Problem

Status
Not open for further replies.
W

wcz

Member level 2
Member level 2
Joined
Jul 17, 2004
Messages
49
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
582
I face a difficulty in solving the following question.

The laplace transform of a signal x(t) that is zero for t<0 is

X(s) = [ s^3 + 2s^2 + 3s + 2] / [ s^4 + 2s^3 + 2s^2 + 2s + 2 ]

determine the laplace transform of the following signal;

y(t) = [t-1][x(t-1)] + dx(t)/dt

Thanks in advanced.
 

Hi..
The solution is
Y(s)= -exp(-s)X'(s)+sX(s)...

where exp is the exponential function and X'(s) is the first derivatve of X(s)...

Hope this helps..
 

Thanks for your reply.
Then, how about the following question.

y(t) = tx(t-1)

With the same given X(s).
Thanks in advanced.
 

The answer should be:

Y(s) = exp(-s)X'(s)
 

Here is the right answer:
Since y(t)=tx(t-1)=(t-1)x(t-1)+x(t-1), then Ly[y]=L[(t-1)x(t-1)]+L[x(t-1)]
=-exp(-s)X'(s)+exp(-s)X(s).
 

    W

    wcz

    Points: 2
    Helpful Answer Positive Rating
In my answer there should have been a negative sign as well plus that extra term that steve10 has shown.
 

Status
Not open for further replies.

Similar threads