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Math Help - Initial values - exponential equation

  1. #1
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    Initial values - exponential equation

    How can i find the initial values for A, k2 and k1 from this equation:
    Y=A*(1-(k2/(k2-k1))*exp(-k2*x)+(k1/(k2-k1))*exp(-k1*x))
    data set:
    x: 0 5 20 30 60 90 120 195 240 360 480
    y: 0 0.0001 0.044 0.161 0.437 0.754 1.134 1.917 2.548 3.933 5.215
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  2. #2
    MHF Contributor

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    Re: Initial values - exponential equation

    "Initial" values? What is "initial" about them? You just want to find the values of A, k1, and k2. Since those are 3 unknown values, you need three equations. If the given function exactly satisfied your given values, any three (x,y) pairs would work. If it is possible that it doesn't, the best fit would be given by using points as much separated as possible- (0, 0), (90, 0.437), and (480, 5.215).
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