Question about Texas Instruments TI-89 Calculator

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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

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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).

Posted on Feb 01, 2010

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Just bought this Ti-89 and I can't graph a Diff - 12-29-2016 image003-bfbopuxcybmyb3dztz0mwecn-3-0.jpg

Posted on Mar 17, 2017


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1 Answer

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

I keep getting undefined variable error when i try to graph

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.

Sep 30, 2009 | Texas Instruments TI-89 Calculator

2 Answers

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.

Mar 19, 2009 | Texas Instruments TI-84 Plus Calculator

1 Answer

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.

Mar 11, 2009 | Texas Instruments TI-89 Calculator

1 Answer

How do you restore a TI-89 Titanium clac

Perhaps one of the following sources will be helpful:

To reset the TI-89 family, TI-92 family and Voyage 200 graphing calculators, press [2nd] [6] (reads MEM over the key). The [F1] menu appears and contains the following options:
  • All RAM - Clears all variables and programs from RAM only. This will not delete items from Archive or Apps.
  • Defaults - Does not clear any files from the calculator. Instead, this option resets the calculator settings to default, including the Mode, Graph Format, Table Setup, and other settings.
  • Vars - Clears all variables from Archive (Flash ROM). This option will NOT delete Apps or variables stored in RAM memory.
  • Apps - Clears all Apps from Archive. This will not delete any variables.
  • Both - Will clear all Apps and Variables from Archive. This will not delete any Variables from RAM.
  • All Memory - Clears everything from RAM and Archive, leaving only the Calculator OS and its components.
For example, I think you will want to follow the last step above... which would be to press [2nd] [6] [F1] [1] [1] [ENTER] [ENTER].

Also, if you are looking to clear all the RAM in another way I would take a look at the guidebook, which is downloadable from the following site in PDF format.

Take a look at page 951 and 952 for another way to clear the RAM

Jan 29, 2009 | Texas Instruments TI-89 Calculator

2 Answers

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...

Jan 11, 2009 | Texas Instruments TI-89 Calculator

1 Answer

Plz help

Try not to set your first variable as zero
thats not a lot but thats what happened to me in my class

Jul 17, 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

3 Answers

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. )

Sep 19, 2007 | Texas Instruments TI-89 Calculator

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