Question about Texas Instruments TI-89 Calculator

# I keep getting undefined variable error when i try to graph

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• Texas Instru... Master

Hello,
The default variable for the integral is x. If you have a product between two litteral symbols the * must be inserted. Arguments of functions must be enclosed between parentheses. To avoid errors clear the variables before the integration: [2nd][F6:Clean Up] [2:NewProb][ENTER]ENTER]

Hope it helps.

Posted on Sep 30, 2009

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Posted on Jan 02, 2017

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## Related Questions:

### 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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### Reset

You referenced a variable that is not currently defined. For example, you referenced a stat variable when there is no current calculation because a list has been edited, or you referenced a variable when the variable is not valid for the current calculation, such as a after Med-Med.

Jun 06, 2013 | Texas Instruments TI-83 Plus Calculator

### Every time i try to graph a function "undefined variable" pops up on the screen and then i can't get anywhere after that

Do you have a function somewhere (not necessarily y1) that is attempting to graph. You can check this by going into the Var-Link menu (2nd MINUS) and searching for a function variable. If that doesn't work check the function you're trying to graph and see if it has a variable in it that is supposed to be a multiplication (xy instead of x*y) or if somehow the variable you meant to use got deleted

Aug 08, 2011 | Texas Instruments TI-89 Calculator

### 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

### 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).

Feb 01, 2010 | Texas Instruments TI-89 Calculator

### I cannot plot graph in my Ti 89 graphing calculator

That means one (or more) of the variables you have in your function is not defined. Check to make sure you didn't misspell any variable name. Also, check to make sure you didn't run two variable names together. "ab" is the variable ab, not a times b.

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### Can not display the graphs of functions

Hello,
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. 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.

Mar 11, 2009 | Texas Instruments TI-89 Calculator

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