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Calculators How do I graph (In TI-89 titanium) where Y is the independent Variable?

  1. Sep 9, 2007 #1
    Right now I'm doing Centroids in my math class. we are given two functions.
    X=-y
    and
    X=2y-y^2.

    My question is, how do I graph these two functions on my TI-89 titanium. The Y=editor is displayed as y(x). Is there a way to change it to X(y). I was able to plot it out on paper, but I use my calculator to check my work. Any help is appreciated thanks.
     
  2. jcsd
  3. Sep 9, 2007 #2

    G01

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    Off the top of my head, I can't think of any way, but I don't do much graphing with mine. The easiest solution I can think of is (This may be stupid of me to point out, since it's kind of obvious) to replace y with x in the calculator and vice-versa and just keep track of the change of notation in your head?

    If there is a way to do what you ask, I'm sure someone here know how to, but I thought I'd point out the "quick and dirty" fix for the problem.:smile:
     
  4. Sep 9, 2007 #3

    Hurkyl

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    A rotation works too: (x, y) --> (y, -x). That way, you can undo the rotation 'by hand'. :smile:
     
  5. Sep 10, 2007 #4
    rotate your calculator by pi/2 :)
     
  6. Sep 10, 2007 #5

    George Jones

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    Use PARAMETRIC mode, setting, for example, y = t and x = 2t - t^2.
     
  7. Sep 10, 2007 #6
  8. Sep 10, 2007 #7
  9. Sep 10, 2007 #8

    George Jones

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    I can't tell problem you're having. In PARAMETRIC mode, I get the exact graph. I set tstep = 0.05.
     
  10. Sep 10, 2007 #9
    You should just be able to use the SOLVE function in the catalog from the main screen.
    I can't remeber what menu it is under, it may be ALGEBRA.
    SOLVE(X=2y-y^2,y) {ENTER}
    The copy the answer into the Y editor. If there are roots, you have to manually enter each root i.e if you want to look at the sq_rt of x you have to input two seperate equations

    y=sq_rt(x)
    and
    y= -sq_rt(x)
     
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