Results 1 to 2 of 2

Math Help - Exponential Equation

  1. #1
    Newbie
    Joined
    Apr 2010
    Posts
    1

    Exponential Equation

    Help!

    1. 2^(2x) + 4 =17 x (times) 2^ (x-1)

    i have been taught to find a common expression and denote it as y
    i.e. 3 ^2x -10 times 3 ^x + 9=0; y= 3^x

    but do not know how to do that here
    Follow Math Help Forum on Facebook and Google+

  2. #2
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    Quote Originally Posted by sarahhardtke View Post
    Help!

    1. 2^(2x) + 4 =17 x (times) 2^ (x-1)

    i have been taught to find a common expression and denote it as y
    i.e. 3 ^2x -10 times 3 ^x + 9=0; y= 3^x

    but do not know how to do that here

    Note that 2^{x-1} = 2^x \cdot 2^{-1} = \frac{1}{2}\,2^x

    2^{2x} + 4 = \frac{17}{2} \cdot  2^x

    2^{2x} - \frac{17}{2}\,2^x + 4 =0

    This is now in the form of a quadratic equation in 2^x so you can use the quadratic formula.
    Recall that for all real x: 2^x > 0
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Exponential equation
    Posted in the Algebra Forum
    Replies: 2
    Last Post: October 28th 2010, 04:50 PM
  2. Exponential Equation
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: November 12th 2009, 12:19 PM
  3. Exponential equation
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: June 2nd 2009, 04:52 AM
  4. exponential equation
    Posted in the Algebra Forum
    Replies: 4
    Last Post: October 22nd 2008, 06:44 PM
  5. Please help with this exponential equation
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: November 22nd 2007, 12:27 AM

Search Tags


/mathhelpforum @mathhelpforum