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  • Sep 20, 2009, 03:01 PM
    j4gym
    Pre calc equation
    How do you solve this problem?
    3^2x+ 3^x -12 = 0
    and can you do the steps for me to also please.
  • Sep 20, 2009, 08:11 PM
    Perito
    Quote:

    How do you solve this problem?
    3^2x+ 3^x -12 = 0
    It's fairly simple as soon as you realize you can factor it.





    Quote:

    and can you do the steps for me to also please.
    I wish I could (actually, I don't -- but I'm lazy). Just create two equations from the above equation. Move the constant to the right in each equation and take the logarithm of both sides.
  • Sep 20, 2009, 11:22 PM
    Unknown008

    Okay, the easiest way to do this is by a simple substitution.

    Let

    Then,






    Now, you can solve it like any other quadratic;



    Then,

    y = -4or
    y = 3

    Replace y by 3^x




    Since 3^x cannot be negative, it must be the other one.



    So, x = 1

    :)

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