Results 1 to 2 of 2

Math Help - Precalculus

  1. #1
    Newbie
    Joined
    Jan 2009
    Posts
    15

    Precalculus

    Find f -1(x) for the one-to-one function


    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570

    Inverse of a function

    Hello keadyjr
    Quote Originally Posted by keadyjr View Post
    Find f -1(x) for the one-to-one function


    What you have to do here is to let y = f(x) = \frac{4x-9}{7}, and then make x the subject of the formula.

    So 7y = 4x-9

    \Rightarrow 4x = 7y+9

    \Rightarrow x = \frac{7y+9}{4} = g(y), say.

    So what now have is that f:x \rightarrow y (in other words, f is the function that maps x onto y), and g:y \rightarrow x. So g maps y back onto x. Therefore g is therefore the inverse of f; i.e. g = f^{-1}

    Now it doesn't matter what letter is used for the parameter that's fed into a function, and it's usual to use x rather than y. So we would usually write:

    f^{-1}(x) = \frac{7x+9}{4}

    I hope that clears it up OK.

    Grandad
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Precalculus
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: May 21st 2009, 12:22 PM
  2. Precalculus
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 22nd 2009, 01:20 PM
  3. Precalculus
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 22nd 2009, 01:50 AM
  4. Precalculus
    Posted in the Pre-Calculus Forum
    Replies: 0
    Last Post: May 26th 2008, 10:01 AM
  5. Need PreCalculus Help
    Posted in the Algebra Forum
    Replies: 4
    Last Post: February 1st 2006, 07:26 AM

Search Tags


/mathhelpforum @mathhelpforum