1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Exponential equation help

  1. Jul 17, 2008 #1
    Hello all, I can't believe I having a hard time with this problem but...I am :cry:

    1. 2^(x^2) X 4^(2x) = 1/8

    2. make the bases the same?

    2^(x^2) X 2^((2x)^2) = 1/8
    2^(3x^(2)) = 1/8
    (log1/8)/(log2) = 3x^(2)
    x^(2) = -1

    I know I am doing it wrong. Any help would be greatly appreciated. Thanks,
  2. jcsd
  3. Jul 17, 2008 #2


    User Avatar
    Homework Helper

  4. Jul 17, 2008 #3


    User Avatar
    Homework Helper

    The general rule for "exponentiated exponents" is

    [tex](a^b)^c = a^{(b \cdot c)[/tex], for a positive base a .

    For this problem, you will end up with a quadratic equation in x, with two solutions.
    Last edited: Jul 17, 2008
  5. Jul 17, 2008 #4
    great! thanks so much. Just a stupid mistake on my part, I knew that :uhh:
  6. Jul 18, 2008 #5
    I believe you end up with two imaginary solutions; My guess is that you should just show your work until you run into negative square root.
  7. Jul 18, 2008 #6


    User Avatar
    Homework Helper

    You actually get two real roots.
  8. Jul 18, 2008 #7
    I found the same, you should get two real roots.
  9. Jul 18, 2008 #8
    Oh, I see what I did wrong, I had [tex]2^{x^2}(2^x + 2^x)=1/8[/tex], instead of [tex] 2^{x^2}*2^x*2^x=1/8[/tex]
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook