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Logarithm equation

  1. Oct 18, 2004 #1
    I need to solve 7^2x - 5*7^x - 24 =0. Am I on the right track by starting with 7^2x - 35^x - 24 = 0?
     
  2. jcsd
  3. Oct 19, 2004 #2

    Tide

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    Let [itex]y = 7^x[/itex] and see where that leads! :-)
     
  4. Oct 19, 2004 #3
    ?

    I sorry, can elaborate. Are you talking about ax+by+c=0. If so, I'm still a little confused.
     
  5. Oct 19, 2004 #4

    Tide

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    You did say "logarithm equation" in the title so I assumed you meant you want to solve this equation:

    [tex]7^{2x} - 5 \times 7^x - 24 = 0[/tex]

    If so then set [itex]y = 7^x[/itex] and since [itex]7^{2x} = \left(7^x\right)^2[/itex] your equation becomes

    [tex]y^2 - 5y - 24 = 0[/tex]

    which you can easily solve for y from which you can obtain x.
     
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