Results 1 to 4 of 4

Math Help - Logarithmic Equation

  1. #1
    Senior Member Stroodle's Avatar
    Joined
    Jun 2009
    Posts
    367

    Logarithmic Equation

    Hi. I'm having trouble trying to solve the following equation for x

    2^{2x}-12\times2^x+32=0

    Any help will be appreciated. THanks
    Last edited by Stroodle; September 27th 2009 at 02:01 AM. Reason: clarity
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,829
    Thanks
    1602
    Quote Originally Posted by Stroodle View Post
    Hi. I'm having trouble trying to solve the following equation for x

    2^{2x}-12\times2^x+32=0

    Any help will be appreciated. THanks
    Let X = 2^x, so that the equation becomes

    X^2 - 12X + 32 = 0

    (X - 8)(X - 4) = 0

    X = 8 or X = 4.


    Thus 2^x = 8 or 2^x = 4.


    It should be pretty obvious that x = 3 or x = 2.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Jun 2008
    Posts
    53
    Quote Originally Posted by Stroodle View Post
    Hi. I'm having trouble trying to solve the following equation for x

    2^{2x}-12\times2^x+32=0

    Any help will be appreciated. THanks
    for this question, you don't need to use logarithm.

    let 2^x be y.
    y^2-12y+32=0
    (y-4)(y-8)=0

    y=4 or y=8
    2^x=4 or 2^x=8
    2^x=2^2 or 2^x=2^3
    By comparing indices,
    x=2 or 3
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member Stroodle's Avatar
    Joined
    Jun 2009
    Posts
    367
    Thanks heaps for your help guys. Knew it would be something simple that I missed.
    Was in the logarithm section, so I was trying to do it with logs...
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Logarithmic equation
    Posted in the Algebra Forum
    Replies: 2
    Last Post: October 15th 2010, 09:14 AM
  2. Logarithmic Equation
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: November 12th 2009, 12:54 PM
  3. logarithmic equation
    Posted in the Algebra Forum
    Replies: 1
    Last Post: May 13th 2009, 01:55 PM
  4. logarithmic equation
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: May 11th 2009, 03:52 PM
  5. logarithmic equation
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 26th 2008, 08:25 PM

Search Tags


/mathhelpforum @mathhelpforum