Results 1 to 2 of 2

Math Help - Calculus: Exponential Functions

  1. #1
    Deltaboy
    Guest

    Calculus: Exponential Functions

    can someone help me with this problem..



    well, I thought that f(x)= 2*e^(-x) was pretty close except when x at 2, y is not (2/9) but instead it's .5

    any one can help?
    thanks..
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    10,185
    Thanks
    404
    Awards
    1
    Quote Originally Posted by Deltaboy View Post
    can someone help me with this problem..



    well, I thought that f(x)= 2*e^(-x) was pretty close except when x at 2, y is not (2/9) but instead it's .5

    any one can help?
    thanks..
    Well it goes through (0, 2), so
    2 = Ca^0 \implies C = 2

    So the curve is f(x) = 2a^x.

    Again, the curve goes through \left ( 2, \frac{2}{9} \right ) so,
    \frac{2}{9} = 2a^2

    \frac{1}{9} =  a^2

    Thus
    a = \pm \frac{1}{3}

    Now, we may exclude the negative solution because the curve for this is, to put it mildly, psychotic. Thus
    f(x) = 2 \left ( \frac{1}{3} \right ) ^x

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: June 9th 2011, 10:54 AM
  2. Replies: 3
    Last Post: February 27th 2011, 04:28 AM
  3. Replies: 4
    Last Post: May 16th 2010, 12:32 AM
  4. exponential functions
    Posted in the Algebra Forum
    Replies: 1
    Last Post: August 24th 2009, 07:09 PM
  5. Exponential Functions
    Posted in the Algebra Forum
    Replies: 3
    Last Post: January 16th 2009, 04:57 PM

Search Tags


/mathhelpforum @mathhelpforum