Need some quick Math help (Rational Functions etc)

Discussion in 'Homework Help' started by Tbo, Feb 1, 2015.

Need some quick Math help (Rational Functions etc)
  1. Unread #1 - Feb 1, 2015 at 5:05 AM
  2. Tbo
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    Need some quick Math help (Rational Functions etc)

    Any help would be appreciated :p
    I'm only looking help for possibly question 2 and 3.

    So; f(x)=(2x-3)/(x-2)

    1) Sketch the graph (easy enough, simple rational function)
    2) Find the inverse and state the domain of the inverse
    (When I found the inverse, it solved to be the exact same function (f(x)=f^-1(x)), i'm wondering if this is possible or if I've solved it wrong) f^-1 Domain= f(x) Range so ya
    3) Find the values of x for which f(x)=f^-1(x)
    This is the one that (sort of) has me stumped. Since they are the same function, do I write infinite solutions? Because it's a 2 mark question I'm assuming there's more to it.


    Thanks for any help.
     
  3. Unread #2 - Feb 1, 2015 at 3:08 PM
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    Need some quick Math help (Rational Functions etc)

    f(x)=(2x-3)/(x-2)
    f^-1(x) = 1/f(x)

    Therefore f^-1(x) = (x-2)/(2x-3) which therefore the domain and range are definitely not the same since the vertical asymptote is now different... went from x= 3/2 to now x=2.

    As for when they're equal set f^-1(x) = f(x)
    (x-2)/(2x-3) = (2x-3)/(x-2)
    Isolated, distribute and solve.

    0=(2x-3)^2/(x-2)^2 and then solve for values of x.
     
  5. Unread #3 - Feb 1, 2015 at 3:13 PM
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    Need some quick Math help (Rational Functions etc)

    If you want me to write it out by hand and include a full solution let me know through pm or reply here. I thought I'd just get you started
     
  7. Unread #4 - Feb 2, 2015 at 12:54 AM
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    Need some quick Math help (Rational Functions etc)

    That would be the reciprocal, the inverse is when you swap y with x (in this case, x=(2y-3)/(y-2), solve for y. Sent you a pm though, ty.
     
  9. Unread #5 - Feb 2, 2015 at 1:52 AM
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    Need some quick Math help (Rational Functions etc)

    Wasn't digging typing anything out so I wrote it.

    http://imgur.com/qytNsZo.

    You can try it yourself on any graphing calculator if you're really unsure :)
     
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