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Homework Help: Cooling process - Exponential functions

  1. Mar 1, 2010 #1
    1. The problem statement, all variables and given/known data

    Hello i am doing a cooling experiment and i want to know the following:

    y=28.49e^(-0.03890*800) +26.51 (note the 26.51) is not part of the exponential.

    What is y? and I was wondering whether this would go ever go through the x axis?

    Thanks people!

    2. Relevant equations


    3. The attempt at a solution

    I have been putting the info into my calculator and i just cant seem to be able to graph it (TI-84) and from my knowledge of exponentials i don't think that an exponential like this can be below the x axis, but i may very well be wrong.

    Thanks again
  2. jcsd
  3. Mar 1, 2010 #2


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    Homework Helper

    When y=0

    Aekx+B= 0 ⇒ ekx=-B/A

    and ekx is never less than zero for all values of x. Thus it does not cross the x-axis.
    Last edited: Mar 1, 2010
  4. Mar 1, 2010 #3
    Thanks mate!
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