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Inverse of s(x)=[1+f(x)]/[1-f(x)]

  1. Oct 28, 2012 #1
    f is a one to one function with inverse f^-1, and we are asked to find the inverse of s(x)=[1+f(x)]/[1-f(x)]

    My attempts leave me with s^-1(x)= [f^-1(1-x)]/[f^-1(-x-1)] and I don't think this is correct. I can't find any examples of problems like this online.
     
  2. jcsd
  3. Oct 28, 2012 #2

    tiny-tim

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    welcome to pf!

    hi caitlinbennet! welcome to pf! :smile:

    (try using the X2 button just above the Reply box :wink:)
    so f(x) = … ?

    and what does that tell you about s-1 ? :wink:
     
  4. Oct 28, 2012 #3
    Re: welcome to pf!

    Is s-1 a composition of f-1.. I'm definitely missing something silly here...
     
  5. Oct 28, 2012 #4

    tiny-tim

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    f(x) = … ?
     
  6. Oct 28, 2012 #5
    (1+s(x))/1-s(x)?
     
  7. Oct 28, 2012 #6
    really have no idea where to start..
     
  8. Oct 29, 2012 #7
    I found the answer on wolfram alpha, I can invert normal functions but this one has me totally stumped.
     
  9. Oct 29, 2012 #8

    tiny-tim

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    hi caitlinbennet! :smile:

    (just got up :zzz:)
    ok, so suppose s(y) = x

    then y = s-1(x), and y = f-1(f(y)) = … ? :wink:
     
  10. Oct 29, 2012 #9
  11. Oct 29, 2012 #10

    tiny-tim

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    i mean, in terms of s(y) ?
     
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