# Error on the TI-89 Titanium

• Calculators
• kald13
In summary, the problem is that the - sign is not binding to anything in the notation. This problem is caused by the different minus keys on the TI-89.

#### kald13

I was working with a much longer equation and receiving a result I didn't expect, and finally narrowed it down to the following section:

$2(-2^3)-3(-2^2)$

2(-2^3) is correctly calculated as -16 independently, and 3(-2^2) is correctly calculated as 12 (again, independently) for a difference of -28, but my calculator is returning -4.

No matter how I enter the equation, the only way I obtain a correct result is by first defining a variable as -2 and then substituting that variable in for -2 in the equation.

Is this problem repeated on anyone else's unit? And if you've encountered this sort of problem before, is there a way to correct it?

Is -22 intended to mean -(22) or (-2)2?

I will use (-) for the negative operator

I hope 3((-)2^2) is not calculated as 12 that would be very wrong

3((-)2^2)=-12 due to operator precedence

2((-)2^3)-3((-)2^2)=2((-)(2^3))-3((-)(2^2))=-4

perhaps you had intended to write

2(((-)2)^3)-3(((-)2)^2)=-28

There are a number of different ways to enter the problem to achieve the intended result. I have tried a few variations, all with the same results.

$(2*((-2)^3))-(3*((-2)^2))=-4$
$(2*((z)^3))-(3*((z)^2))=-28$

This is a piece of the derivative of a function, and -2 is one of the zeros of the derivative signifying a local maximum in the function. The intent is to solve the equation when z=-2 (among other values)

Incidentally, entering the equation in the calculator as I originally did produces the same results; the intent is not to find -(2^3) (which is -8) but (-2^3) (which is also -8, but for a different reason).

$(2*-2^3)-(3*-2^2)=-4$
$(2*z^3)-(3*z^2)=-28$

^Of those four only the first one is surprising. If that input gives that output I am quite confused.
What happens if you enter
2((0-2)^3)-3((0-2)^2)
?
I do not have a ti89 handy
I do know that the manual gives the example
((-1)2)^2=4
(-)2^2=-4

lurflurf said:
I will use (-) for the negative operator

I hope 3((-)2^2) is not calculated as 12 that would be very wrong
The above is a very silly use of parentheses.

(-2)2 should evaluate to +4.
-22 should evaluate to -4.
lurflurf said:
3((-)2^2)=-12 due to operator precedence
The trouble with this notation, above, is that the - sign is not binding to anything.
lurflurf said:
2((-)2^3)-3((-)2^2)=2((-)(2^3))-3((-)(2^2))=-4

perhaps you had intended to write

2(((-)2)^3)-3(((-)2)^2)=-28

^It is not silly, it is to distinguish between the unary and binary operators. It is the same notation used on the calculator keypad. For you special
3(-<<<the unary one>>>2^2)

to quote the manual

$$\text{Important: Use }\bbox[3px,border:2px solid black]{\phantom( - \phantom)}\text{ for subtraction and use }\bbox[3px,border:2px solid black]{(-)}\text{ for negation.}$$

Last edited:
Mark, not sure if you know it, but TI-89 has two different minus keys.

The one with "(-)" is an unary "change sign" operator, the other is a binary "minus". Hence the "(-)" and "-" notation is just reflecting the reality.

Borek said:
Mark, not sure if you know it, but TI-89 has two different minus keys.
No, I didn't know that. That notation seems to be fairly new in calculators. Calculators have been distinguishing between the unary minus and binary subtraction operator for a long time, but using +- for the unary operation and - for subtraction.

I didn't realize that lurflurf was using (-) to mimic that key on the TI-89.
Borek said:
The one with "(-)" is an unary "change sign" operator, the other is a binary "minus". Hence the "(-)" and "-" notation is just reflecting the reality.

Mark44 said:
No, I didn't know that. That notation seems to be fairly new in calculators. Calculators have been distinguishing between the unary minus and binary subtraction operator for a long time, but using +- for the unary operation and - for subtraction.

I didn't realize that lurflurf was using (-) to mimic that key on the TI-89.

The [(-)] key doesn't mimic a [+/-] key, it correctly implements the operation of negation in normal mathementical notation which is to negate the following argument, whereas the normal implementation of a [+/-] key is to negate the argument currently displayed.

Note that page 943(!) of the manual states:
To enter a negative number, press [(-)] followed by the number. Post operations and exponentiation are performed before negation. For example, the result of -x2 is a negative number, and -92 = -81.

Now that I look at the picture of my TI, I think it is time to clean it

## What is "Error on the TI-89 Titanium"?

"Error on the TI-89 Titanium" refers to a message that appears on the screen of the TI-89 Titanium calculator when there is an issue with a calculation or function.

## Why am I getting the "Error on the TI-89 Titanium" message?

There are a few possible reasons for this message, such as a syntax error in the calculation, using a function incorrectly, or attempting to perform a calculation that the calculator is not capable of.

## How can I fix the "Error on the TI-89 Titanium" message?

To fix this error, you can try reviewing and correcting any errors in your calculation, checking the user manual for correct usage of functions, or using a different method or function to perform the calculation.

## Is the "Error on the TI-89 Titanium" message a serious issue?

In most cases, this message is not a serious issue and can be easily resolved by correcting the error in the calculation. However, if the error persists or you are unable to identify the issue, it may be necessary to seek further assistance.

## Can I prevent the "Error on the TI-89 Titanium" message from appearing?

While it is not possible to completely prevent this message from appearing, you can minimize the chances by carefully checking your calculations and using functions correctly. It is also helpful to have a good understanding of the calculator's capabilities and limitations.