Archive for April, 2015

How many apps does the ti89 hold

Thursday, April 30th, 2015

Q: Also, can the TI89 have more than one app installed at the same time, due to space requirements?

A: Absolutely. Typically users have more than 20 apps installed on their TI89s. There is plenty of available memory.

Probability density functions

Wednesday, April 29th, 2015

1-Moment Generating functions are to be added.

2-Probabilty Density Function

They are under F3

3- Uniform Density Function

Also under F3. Option 2 in dropdown lets you accumulate.

4- Cumulative Density Function. Also under F3. cumulative option is in the dropdown options.

Apps are locked after dropping TI89 calculator

Wednesday, April 29th, 2015

> Q: I dropped my calculator and for some reason when I tried to access the apps, it asked for my activation codes again. Now my apps are locked. Is there anything I can do? >

A: Pull up that email with the activation keys that you received after purchasing the apps. You would just have to reinstall the apps and reenter the same activation keys as before. (Redownload the apps if needed at )

Undefined Variable Error After installing App

Wednesday, April 29th, 2015

I installed the Business stats app and activated it perfectly. When I went to open it, it gave me a memory error and now says ” Undefined variable” ESC=Cancel and everytime I click it, it comes right back and won’t let me exit or do anything. I can’t get to the memory menu to clear any memory. What shall I do?

This memory error can be resolved as follows:

Press ESC up to 100 times until error disappears.

Next, 2nd 6 F1 reset all memory.

Reload app and all will be well.


Sum of converging telescoping series

Tuesday, April 28th, 2015

How can the answer to this converging telescoping series be found on the 89 using the sequences and series module of calculus made easy ?

Straightforward , under f2 C enter this series as 2/(n^2-1) with a starting value of N=2
Notice the series is undefined when n=1.

Finally , your answer comes to be 1.5 or 3/2

Of course, this tool finds the sum of any converging series. To test for convergence you may just use the all on one convergence tester under F2 that will tell you step by step whether your series converges or diverges.

Business Statistics App

Monday, April 27th, 2015

> Q: I was wondering if this app does one-tailed and two-tailed rejection region tests. >
> A: yes. It does that for all types of statistical tests, step by step. You may select at the levels too 5% , 1% etc

Green’s theorem

Sunday, April 26th, 2015

Q: I’m using the Green’s Theorem portion of the Calculus Made Easy app. It does not ask for the pathway etc… How do I enter the attached problem ?

A: Here we go , enter as follows
M,N = [y-x , 2x-y]

Now lets think about the path for moment: it is an ellipse starting at 2,0 passing through 0,2 , -2,0 and 0,-2 and back to 2,0 correct?
Ellipse equations in rectangular coordinates are : x^2/a^2 + y^2/b^2 = 1 , here a=2 , b=1 .Solving for y^2 yields:
y^2= 1-1/4*x^2 . Solving for y yields y= – + SQRT(1-1/4*x^2) which are lower and upper y bounds , enter them as such
and x bounds are [-2,2] . So the path is defined using x and y as rectangular bounds.

Memory Error when running Made Easy app

Sunday, April 26th, 2015

Hello I am having an issue running physics made easy. I keep getting a memory then an undefined variable error. This is on my calculator. Any ideas?

Ans: Reason is very likely that your TI89s memory is filled up with preloaded apps .

Here is the simple solution in 3 steps:
1. Backup your TI89 if you wish (remember that preloaded apps can be downloaded freely at TI’s website any time)

2. Press 2nd 6 F1 , select reset all memory. ENTER

3. retransfer APP and all will be well!

Parametrization of a curve

Sunday, April 26th, 2015

Thanks, works perfectly for #6 where the function is simple [2y,2x] and the slope was simply 3t.

I tried the exact same procedure on #7. however the function is now [8(4x+9),18(4x+9y)] and the slope is -1/6 from points (-9,4) to (3,2). I wonder if the variable bounds are [-9,3]? The book gives a solution of 400.

Ans: Correct on the bounds. Recall the param. uses y-y1=-1/6*(x-x1) , using 3,2 we have y-2=-1/6*(x-3) , solving for y and using t yields:

y=-1/6t + 5/2 . ok?

Now let t run from -9 to 3 and you got it!

Finding sequence formulas and convergent/divergent sums

Friday, April 24th, 2015

How do I do problems like finding the sequences formula or sums of convergent (OR IF IT DIVERSES)?

Both problems can be solved using the Sequence and Series module in Calculus Made Easy using your trusty TI 89 . The Sequence Formula Finder under F1 4 will find formulas for geometric and arithmetic sequences. You enter the first 4 terms of a sequence and voila you get the formula. To then find the sum , just go to F2 C and enter the nth term of the series to get a number (converges) or infinity (diverges) . That simple. Recall that you have the All-in-One Convergence Tester under F2 7 that will perform the tests of convergence such as nth term test, geometric series test , integral test , alternating series test, ratio test AUTOMATICALLY. Best of all : all steps are shown . A true blessing.