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

Click For Summary

Discussion Overview

The discussion revolves around how to graph two functions, X = -y and X = 2y - y², on a TI-89 Titanium calculator, where the standard graphing mode is set for y as a function of x. Participants explore various methods to adapt the calculator's functionality to accommodate the functions expressed in terms of y.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests replacing y with x and vice versa in the calculator while keeping track of the notation change.
  • Another proposes a rotation transformation of the coordinates, suggesting (x, y) transforms to (y, -x) to facilitate graphing.
  • A different approach involves using PARAMETRIC mode, with y set as a function of a parameter t, such as y = t and x = 2t - t².
  • One participant mentions using the SOLVE function to find y in terms of x, indicating that roots must be manually entered for certain functions.
  • Another participant expresses difficulty in replicating the graph despite trying the suggested methods, indicating a need for further clarification.

Areas of Agreement / Disagreement

Participants present multiple competing methods for graphing the functions, and there is no consensus on a single best approach. Some methods are suggested as potential solutions, but participants express varying levels of success with these methods.

Contextual Notes

Some participants mention specific settings, such as tstep = 0.05 in PARAMETRIC mode, but there are unresolved issues regarding the exact implementation of these methods on the calculator.

Migkiller
Messages
8
Reaction score
0
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.
 
Computer science news on Phys.org
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:
 
A rotation works too: (x, y) --> (y, -x). That way, you can undo the rotation 'by hand'. :smile:
 
Migkiller said:
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.
rotate your calculator by pi/2 :)
 
Migkiller said:
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.

Use PARAMETRIC mode, setting, for example, y = t and x = 2t - t^2.
 
Migkiller said:
I'm trying your guys' suggestion but I still can't replicate the graph. This is the graph I'm trying to produce but I don't need to add the endpoint where both functions intersect.
The graph is located in the link at the bottom page.

I can't tell problem you're having. In PARAMETRIC mode, I get the exact graph. I set tstep = 0.05.
 
Migkiller said:
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.

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 separate equations

y=sq_rt(x)
and
y= -sq_rt(x)
 

Similar threads

Replies
4
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
7K
  • · Replies 1 ·
Replies
1
Views
5K
  • · Replies 5 ·
Replies
5
Views
5K
  • · Replies 1 ·
Replies
1
Views
17K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 1 ·
Replies
1
Views
5K
  • · Replies 3 ·
Replies
3
Views
7K
  • · Replies 2 ·
Replies
2
Views
7K