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Math Help - population growth problem

  1. #1
    Newbie mockingjay95's Avatar
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    population growth problem

    dy/dx=1-0.2y, solve for y when y=0, x=0
    This is how I solved it dy/(1-0.2y)=dx <=> -5* (-0.2dy/1-0.2y)=dx
    integrating the equation, ln(abs) 1-0.2= x+c/-5
    1-0.2y=e^(-x/5+c) <=> 1-0.2y=ce^-x/5
    My final equation is y=e^(-x/5)-1/-0.2 after plugging in y=0 and x=0
    Is it correct?
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  2. #2
    Newbie mockingjay95's Avatar
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    Re: population growth problem

    can anyone check my work, please?
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  3. #3
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    Re: population growth problem

    Check your final calculations in solving this D.E.
    I found y=5[1-e^(-x/5)]

    MINOAS
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  4. #4
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    Re: population growth problem

    A quick hint for using MHF - unanswered questions stand out from the rest, so it's not in your interest to answer your own question. Unless you've found the solution, of course.

    I think your answer is correct.

    - Hollywood

    P.S. I interpreted y=e^(-x/5)-1/-0.2 as y=(e^(-x/5)-1)/-0.2. But the order of operations puts division first, so the correct interpretation is y=e^(-x/5)-(1/-0.2).
    Last edited by hollywood; February 18th 2013 at 09:42 AM.
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