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Homework Help: Laplace Unit Step function

  1. Dec 4, 2012 #1
    1. The problem statement, all variables and given/known data
    y''-4y'-32y={1 when 0<=t<1 and 0 when 1<=t

    2. Relevant equations

    3. The attempt at a solution
    s2L(y) -4sL(y)-32 L(y)=u1(t)

    I am just struggling to figure out if my unit step function is correct.

    Solving for L(y) I get:
    (e-s) / (s(s2 -4s-32))
    but it says I am wrong so im pretty sure I am doing something wrong with the unit step function
  2. jcsd
  3. Dec 4, 2012 #2


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    Science Advisor
    Homework Helper
    Gold Member

    You didn't explain what your notation ##u_1(t)## means. Is it ##u(t-1)##? What you want on the right side is ##u(t)-u(t-1)##.
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