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Log equations AGAIN!

  1. Apr 23, 2007 #1
    1. The problem statement, all variables and given/known data
    Solve the equation:
    2^x multiplied by 4^(x + 5) = 4^(2x - 1)


    2. Relevant equations



    3. The attempt at a solution

    2^x multiplied by 2^2(x+5)=2^2(2x-1)
    x(2x+10)=4x-2
    2x^2+10x=4x-2

    and that's as far as i could get before I was completely stuck. But this could be completely wrong.
     
  2. jcsd
  3. Apr 23, 2007 #2

    danago

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    Gold Member

    When you have [tex]2^x2^{2x+10}[/tex], you dont multiply the indexes, you add them.
     
  4. Apr 24, 2007 #3

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    As danago said, [tex]2^x2^{2x+10}= 2^{3x+10}= 2^{4x-2}[/tex]. That gives a simple linear equation for x.


    However, IF 2x^2+10x=4x-2 had been correct, that shouldn't give you any problem. It is a quadratic equation and, if you can't factor it, you can use the quadratic formula!
     
    Last edited: Apr 25, 2007
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