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Why there is a minus in the power

  1. Jul 12, 2009 #1
    when the two roots s1 and s2 that are different of the homogenius equation
    in normal diff theory i do

    [tex]
    v_c (t)=Ae^{s_1t}+Be^{s_2t}
    [/tex]

    why why in basic circuit theory we do
    [tex]
    v_c (t)=Ae^{-|s_1|t}+Be^{-|s_2|t}
    [/tex]
     
  2. jcsd
  3. Jul 12, 2009 #2

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    I'm afraid you'll have to ask that in a "circuit theory" thread. Whatever the reason, It would have to be a physics reason rather than mathematics. I would suspect there is some physical reason why [itex]v_c(t)[/itex] must be decreasing in time. Are the [itex]s_1[/itex] and [itex]s_2[/itex] complex numbers?
     
  4. Jul 12, 2009 #3
    s1 and s2 are not complex
     
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