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Dylan
Lv 6
Dylan asked in Science & MathematicsMathematics · 4 years ago

Simple Laplace Transform?

dy/dt = 1 - y

y (0) = 4

5 Answers

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  • kb
    Lv 7
    4 years ago
    Favorite Answer

    Apply L to both sides (letting Y(s) = L{y}):

    L{dy/dt} = L{1 - y}

    ==> s Y(s) - y(0) = L{1} - L{y}

    ==> s Y(s) - 4 = 1/s - Y(s).

    Solve for Y(s):

    (s + 1) Y(s) = 4 + 1/s = (4s + 1)/s

    ==> Y(s) = (4s + 1)/(s(s + 1))

    ==> Y(s) = 1/s + 3/(s + 1), by partial fractions.

    Inverting yields y(t) = 1 + 3e^(-t).

    I hope this helps!

  • Dan
    Lv 4
    4 years ago

    yes

  • MyRank
    Lv 6
    4 years ago

    3. dy/dt = 1-y

    L{dy/dt} = L{1-y}

    Sy(s)-y(0) = L{1} – L{y}

    (∵ f’(t)=sf(s)-f(0))

    (∵ L{1} = 1/5)

    y(s)(1+s) = 1/5+4

    y(s) = 1+4s/s(1+s)

    y(s) = A/s + B/(5+1)

    y(s)=1/5+3/5+1

    L-1{y(s)} = 1+3e-t

  • Como
    Lv 7
    4 years ago

    ∫ dy / [ 1 - y ] = ∫ dt

    - log [ 1 - y ] = t + C

    log [ 1 - y ] = K - t

    1 - y = e^(K - t)

    y = 1 - e^(K - t)

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  • JOS J
    Lv 7
    4 years ago

    (1 +4 s )/(s (1 + s))

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