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Homework Help: Signal Transformation

  1. Jan 17, 2009 #1
    1. The problem statement, all variables and given/known data
    Let z1(t) be the signal x(t) delayed by 4 sconds and then sped up by a factr of 3. Let
    z2(t) be the signal x(t) sped up by a factr of 3 and then delayed by 4 sconds. Do z1(t)
    and z2(t) represent the same signal?

    2. Relevant equations

    3. The attempt at a solution
    My answer was no they are not the same

    for the first part
    x1(t) = x(t-4) for the delay of 4 secs

    then sped up
    x2(t) = x1(3t)

    so y1= x(3t-4) or x(3(t-4/3)

    for the second part

    x1(t)=x(3t) sped up
    and x2(t) = x1(t-4) delayed by 4 secs

    so y2= x(3(t-4)) or x(3t-12)

    Is my math correct?
  2. jcsd
  3. Jan 18, 2009 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    Welcome to PF :smile:

    Yes, that looks correct. You probably meant "z1" and "z2" where you wrote "y1" and "y2", but you do have the right idea.
  4. Jan 19, 2009 #3
    thanks for the verification!
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