# 20 Most Recent Texas Instruments TI-89 Calculator Questions & Answers

I had this same problem on my TI 89... You must have accidentally set your calculator to insert mode. To switch it back to the thin cursor, input the following keystrokes... Go to the "2nd" key to enter second function mode. Then press the button with an arrow on it pointing to the left(The key that you use to backspace). Do you see the "INS" lettering above the backspace key? There's your solution :-)

Texas... | Answered on Oct 03, 2019

Nothing's wrong, your calculator is giving you the cosine of 42 radians. If you want the cosine of 42 degrees (which is 0.74314), press MODE, down-arrow to the "Angle" line, press right-arrow, select "2:DEGREE", and press ENTER twice.

Texas... | Answered on Dec 31, 2018

It's simple, buy a new one.

Texas... | Answered on Sep 24, 2018

You can see image below

Texas... | Answered on Jan 08, 2018

TI calculators have an annoying habit of dimming the screen when the batteries are changed so that it appears as if the calculator isn't turning on. Turn the calculator on (or at least press the ON key). Press and release the 2ND key. Press and hold the Up-arrow key for a few seconds and see whether the screen becomes legible.

If this doesn't do it, please append a comment to this post and we'll go on from there.

Texas... | Answered on Oct 14, 2017

Press 2ND MATH to bring up the Math menu. Select "Calculus" and then "integrate." Enter the expression, the variable of integration, the lower limit, and the upper limit, separated by commas. Close the final paren and press ENTER or diamond ENTER.

For example, to calculate the integral from 0 to pi of sin(x) dx, you want

INT(sin(x),x,0,pi)

where INT is the integral sign and pi is the lower-case Greek pi.

Texas... | Answered on Dec 26, 2016

You can see images below

Texas... | Answered on Sep 18, 2016

Type it like this: solve( equation1 and equation2 and moreEquations, {list of variables to solve for})

Put all of your equations right after the opening parenthesis separated by the word and, then a comma, then within curly braces each variable you want to solve for each separated by a comma.

Texas... | Answered on May 01, 2016

Press Mode, use cursor to find the Exponential format and select engineering.

Texas... | Answered on Feb 11, 2016

Hi danagasta,

If my last instructions did not work then you need to reset your RAM. You are missing the negative sign and, I have no idea where you got the absolute value inside the brackets.
Yes, the absolute value are used in books and, on integral tables but, I can asure you that the Ti 89 should not have produce them in this answer.

I'll stand behind that In( -cos(x) / (sin(x)-1)) is the correct answer. You can go ahead and simplify after the calculation to get the answer you want but, that is the good answer that Ti 89 is going to give you for the integral of sec(x).

Errors that do not match the suspected, I am pretty sure that Texas Instruments would have you clear the RAM. I do not like resetting the RAM but, I could not find the cause to why you got the answer you did. And so far no other expert has produced a solution to convince me otherwise.

I was not able to come up with any of the 3 answers MiB8888 did on my Ti 89. I am not saying that they are not good answers, they are book and integral tables answers. You are not going to get them on the Ti 89.

Texas... | Answered on Feb 05, 2016

Sorry you cannot do that in any calculator. A fraction is a rational number, a root of any index is GENERALLY an irrational number. Some exceptions do exist, but in general NO.
Square root (9/16) =3/4

Texas... | Answered on Jan 30, 2016

when i hit 2nd+left+right+on then i saw 'installation in progress' on skin. what i have to do? please help me.

Texas... | Answered on Jan 23, 2016

See captured image below

Texas... | Answered on Jan 10, 2016

There is no points of inflection for this function. See cap images below.

Texas... | Answered on Dec 20, 2015

Texas... | Answered on Apr 17, 2014

#### Popular Tags

476 questions posted

Level 3 Expert

Level 3 Expert