Question about Texas Instruments TI-89 Calculator

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Graphing radical functions

When I graph y = square root of x, or cube root of x, or any root of x, I get an error message saying undefined variable. I don't understand this.

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Re: Graphing radical functions

I have a TI-89 Titanium and I have experienced the same problem. HERE IS HOW TO FIX IT:

Goto " MODE " and scroll down the options until you get to
" COMPLEX FORMAT " change that option to " RECTANGULAR " and press ENTER until you exit out of the " MODE " screen. (very important that you press ' enter ' until you exit because if you don't, it will not save your changes. )

Posted on Mar 15, 2009

Re: Graphing radical functions

I had the same problem, when the term under the root could be <0 the complex mode can't be polar. Changing to another mode graphed it.

Posted on Feb 14, 2008

Re: Graphing radical functions

D(x) = sqrt 3x/2

Posted on Nov 29, 2007

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Ti 84 plus wont graph

You might have used an inappropriate variable name.
For functional graphs y=F(x), the independent variable must be X
For parametric graphs, the independent variable in the x_t and y_t functions must be t.
For polar graphs the independent variable must be Theta, and for sequence graphs, it must be the special wiggly n.
Once you select the type of graph, the independent variable is entered by pressing the key marked X,T, Theta, n.

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Why does the TI-nspire not give complete graphs of cube root and other franctional power functions?

I do not see why it would do that. Maybe you restricted the domain to positive values of the independent variable.
Anyway, my CX CAS has the latest OS version and it draws cube root for positive and negative values of x.
By the way the cube root is made up of one branch only, not 2 like the square root.
Here is a screen capture.


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Everytime I try to do powers and square roots I get an error message

An ERR: MEMORY is given when there is not enough memory to perform the instruction or function. To increase available memory by deleting the contents of any variable (real or complex number, list, matrix, Y= variable, program, Apps, AppVars, picture, graph database, or string), follow these steps. • Press [2nd] [MEM] to display the MEMORY menu.
• Press 2: Mem Mgmt/Del.
• Select a variable or data that needs to be deleted and press [ENTER].
• Use the arrow keys to move the cursor next to the item, and then press [DEL]. The variable or data should now be deleted from the memory.
When deleting programs or Apps, a message asking for confirmation will appear. Select 2:Yes to continue. To leave any variable screen without deleting anything, press [2nd] [MODE].

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Everytime I try to graph an equation my calculator says "error 14 undefined" i don't know how to fix it

Error 14 undefined may occur if you are referencing a variable that currently is not defined

Sep 12, 2011 | Texas Instruments TI-86 Calculator

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Want to graph simple functions , like y = x and get error message:" undefined variable".

From the alpha keyboard type in NewProb and press ENTER.
This will clear the contents of all the one-letter variables a-z.
Open the Y= editor and type in an expression for the function to draw.
You do not have to enter a multiplication sign between a numerical factor preceding the variable x and x. If a factor is a letter you must explicitly use the multiplication sign.

Press the key sequence to draw the graph.

Aug 01, 2011 | Texas Instruments TI-89 Calculator

1 Answer

Just bought this Ti-89 and I can't graph a Diff Eq. I followed the directions from the manual on page 69 and get an error: undefined variable

Even though implied multiplication is accepted generally by the calculator when it involves a number and variable, it leads to errors when it involves two sybmols,
xsin(x) is interpreted as a function called XSIN not X*SIN(X).
Suppose you have a function y1, function of t and you write ty1 the calculator will generate an undefined variable error: It reads ty1 as a variable.To prevent the error message you should write t*y1, showing the multiplication explicitly.
Similarly if you write y1'=0.001y1(100-t) the expression y1(100-t) is interpreted as a function call: the function y1 is called with argument 100-t. If it is what you want you should explicitly express the multiplication and wrtite y1'=0.001y1*(100-t).

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Can not display the graphs of functions

I have a manual in another language than English, so I do no know exactly or remotely what procedure you refer to, but I have recreated an instance where one gets the error you talk about. I give you the picts.8147bde.jpg When I enter [Diamond][Graph] I get the following message.
The graph independent variable is x by default, yet I entered cos(f). The calculator is expecting a function of x and I give it a function of some as other entity. Hence the error message. On the command line you cannot change the argument of Y1. It is x by default.

Hope it clarifies things.

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I am trying to graph r=sqroot(sin2theta) on my ti-89 titanium in polar mode and it is telling me when i try to graph that there is an undefined variable. what do i do?

Did you still need help with this? My suspicion is a missing multiplication sign. Sometimes you need to be very explicit in what you want the calculator to do. Have you tried sqroot(sin(2*theta)) explicitly putting the multiplication symbol in there? I think 2theta is interpreted as it's own variable name...

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How do I solve radical expression and equations using the TI89?

1. square of 12
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3. square root of 128 y raise to 5
4. 6th root of 9 y raise to 2
5. cube root of 24 y raise to 5
6. 10th root of 32 x raise to 5
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8. 4th root of 10000
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Jul 04, 2008 | Texas Instruments TI-89 Calculator

1 Answer

Undefined variable

go to home and type Define x

Apr 13, 2008 | Texas Instruments TI-89 Calculator

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