Results 1 to 8 of 8

Math Help - Inverse of function

  1. #1
    Member
    Joined
    Sep 2012
    From
    US
    Posts
    123

    Inverse of function

    How do I find the inverse of this function?

    y = ln(x + 8)
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
    Posts
    3,764
    Thanks
    78

    Re: Inverse of function

    Quote Originally Posted by Oldspice1212 View Post
    How do I find the inverse of this function?

    y = ln(x + 8)
    Exchange the x and y to get

    x=\ln(y+8)

    and now solve for y. This will be the inverse function.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Sep 2012
    From
    US
    Posts
    123

    Re: Inverse of function

    So x would = e^y+e^8?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
    Posts
    3,764
    Thanks
    78

    Re: Inverse of function

    Quote Originally Posted by Oldspice1212 View Post
    So x would = e^y+e^8?
    Not quite. You are correct that the inverse of the natural log is the exponential base e, but be careful the first step should be

    e^x=e^{\ln(y+8)}

    Can you finish from here?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Sep 2012
    From
    US
    Posts
    123

    Re: Inverse of function

    Oh right! Thanks, I'll get back to you with my answer :P
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Member
    Joined
    Sep 2012
    From
    US
    Posts
    123

    Re: Inverse of function

    Uh I got y = e^x-8
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
    Posts
    3,764
    Thanks
    78

    Re: Inverse of function

    That is correct.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Member
    Joined
    Sep 2012
    From
    US
    Posts
    123

    Re: Inverse of function

    Sweet! Thanks for the hint, I can't believe I forgot that!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. function composition and inverse function
    Posted in the Discrete Math Forum
    Replies: 7
    Last Post: November 10th 2009, 12:18 PM
  2. Replies: 2
    Last Post: October 19th 2009, 02:47 AM
  3. Replies: 2
    Last Post: September 22nd 2009, 08:29 PM
  4. Replies: 0
    Last Post: July 19th 2008, 08:06 PM
  5. Replies: 4
    Last Post: March 17th 2008, 09:45 PM

Search Tags


/mathhelpforum @mathhelpforum