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Math Help - Modelling with exponential fuction.

  1. #1
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    Modelling with exponential fuction.

    The growth rate of a plant during the first week after germination is given by g(t)=ae^(t/2) mm/day, where the time t is measured in days, and a is a constant.

    a) Determine the height of the plant h(t) as a function of the time t, assuming that it was zero at time t=0.
    b)On the first day, the plant grew 1 mm. Determine the constant a.
    c) How much did the plant grow on the fifth day (i.e. between t=4 and t=5)?

    I don't know if I'm doing this right. I got h(t)=a(2e^t/2 - 2) for part a and a=1 for part b. Is that right?
    Last edited by mr fantastic; April 28th 2010 at 06:33 AM. Reason: Re-titled.
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  2. #2
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    I'm assuming the information from A, B and C all apply throughout so:
    I got the same equation but without the parenthesis for A. For B I got
    a = 3/(2*sqrt(e)). hope that helps
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  3. #3
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    Quote Originally Posted by AsSeenOnTV View Post
    I'm assuming the information from A, B and C all apply throughout so:
    I got the same equation but without the parenthesis for A. For B I got
    a = 3/(2*sqrt(e)). hope that helps
    How did you get that for part B?
    And why aren't there parentheses for part A? Isn't "a" a constant, so you can take it out of the integral?

    Edit:
    Okay, I know how to get part B and for part C, I got (2e^5/2 - 2e^2)/(2sqrt(e)-2). Could you verify that you get the same answers as me for part b and c, using the equation I got in part a? And again, why is my part A answer different from yours?
    Thanks!
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