Write the function in terms of unit step functions. find the laplace transform of the given function. f(t) = t, 0 ≤ t < 5 0, t ≥ 5

Respuesta :

The Laplace transform of the given function is [tex]f(s)=\frac{1-e^{-5s}(1-5s) }{s^{2} }[/tex]

Given,

[tex]f(t)=\left \{ {{t, 0\leq t < 5} \atop {0,t\geq 5}} \right.[/tex]

Write the function in unit step function.

[tex]f(t)=t(u_{0}(t)-u_{5} (t))[/tex]

      = [tex]t(1-u_{5}(t))[/tex]                       ∵[tex]u_{0} (t)=1[/tex]

      = [tex]t-tu_{5} (t)[/tex]

[tex]f(t)=t-tu_{5} (t)[/tex]

In order to make it easier to take the Laplace transform of the function, we can follow the steps:

[tex]f(t)=t-tu_{5} (t)[/tex]

      = [tex]t-(t-5+5)u_{5} (t)[/tex]

      = [tex]t-(t-5)u_{5} (t)+5u_{5} (t)[/tex]

[tex]f(t)=t-(t-5)u_{5} (t)+5u_{5} (t)[/tex]

We need to find the Laplace transform of f(t).

Apply Laplace transform on both sides,

£[tex][f(t)=[/tex]£[tex](t)-[/tex]£[tex](t-5)u_{5} (t))+5[/tex]£[tex](u_{5} (t))[/tex]

         = [tex]\frac{1}{s^{2} } -e^{-s}[/tex]£[tex](t)+5(\frac{e^{-5s} }{s} )[/tex]

         = [tex]\frac{1}{s^{2} } -e^{-5s} (\frac{1}{s^{2} } )+\frac{5se^{-5s} }{s^{2} }[/tex]

        = [tex]\frac{1-e^{-5s}+5se^{-5s} }{s^{2} }[/tex]

       = [tex]\frac{1-e^{-5s}(1-5s) }{s^{2} }[/tex]

[tex]f(s) =\frac{1-e^{-5s}(1-5s) }{s^{2} }[/tex]

Learn more about Laplace transform here: https://brainly.com/question/17190535

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