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Find math maximum homework

  1. May 26, 2004 #1
    I've got an assesment task tommorow and one of the questions on the practice exam has got me stumped
    The eqaution is y=21xe^(-.9x) - 12xe^(-.6x)

    The question asks to show how the maximum can be
    e^(0.3x) = 70-63x/40-24x

    If differentiated it and taken out the common factors to get
    21e^(-.9x)(-.9x + 1) - 12e^(-.6x)(-.6x + 1) = 0

    but have no idea how to make it e^(0.3x) = 70-63x/40-24x

    If any one could help i would really appreciate it
  2. jcsd
  3. May 26, 2004 #2


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    First of all, write the answer properly:
    Rewrite the right-hand side as:

    See if you can relate this last expression to the equation giving the critical value for y.
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