Results 1 to 2 of 2

Math Help - explaination required

  1. #1
    Member
    Joined
    Feb 2009
    Posts
    101
    Awards
    1

    explaination required

    Use the substitution y=3^x to solve the equation 3^{2x}-10 . 3^x+9=0

    the problem i need explaining is the first part involving the subsitution for y^2. how does 3^{2x} become y^2

    y^2-10y+9=0

    (y-1)(y-9)=0
    .....

    i can see how the rest of the problem is solved as i have the solution

    many thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,506
    Thanks
    1402
    Quote Originally Posted by decoy808 View Post
    Use the substitution y=3^x to solve the equation 3^{2x}-10 . 3^x+9=0

    the problem i need explaining is the first part involving the subsitution for y^2. how does 3^{2x} become y^2

    y^2-10y+9=0

    (y-1)(y-9)=0
    .....

    i can see how the rest of the problem is solved as i have the solution

    many thanks
    Because 3^{2x} = \left(3^x\right)^2 = y^2.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Explaination?
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 21st 2010, 05:51 PM
  2. in detail explaination
    Posted in the Discrete Math Forum
    Replies: 3
    Last Post: July 21st 2009, 12:31 PM
  3. A quick explaination
    Posted in the Calculus Forum
    Replies: 4
    Last Post: June 9th 2009, 02:02 AM
  4. Factorising explaination
    Posted in the Algebra Forum
    Replies: 4
    Last Post: October 3rd 2007, 08:23 PM
  5. I need and explaination
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 9th 2007, 08:45 PM

Search Tags


/mathhelpforum @mathhelpforum