Should I also buy a Ti89?



#14

I'm not sure what to do here. I'm a high school student who is taking AP Calculus and will be taking the SATs shortly. I've only been using HP calcs for several months and I like the high-tech boost from my Ti-84+. However, I have not yet gotten a chance to try the Ti89. I know that there are a lot more programs available for it and that it is more widely used. Should I buy a Ti89 to accompany my hp 50g and see which I like better? (Please don't be biased, but which type of calc is better for AP Calculus and college level science/math/engineering courses?) Thanks.


#15

I have both, the 89 Titanium and the 50G. They are both good and should both be able to do everything you want. I don't favor one over the other. If I had some weeks/months to go to take a test, I would randomly choose one and concentrate on the math and how to efficiently solve these problems with the picked calculator. I would never take both and probably get confused while taking the test - i.e. trying to use RPN on the TI or some such ;-)

#16

If you're referring to the SAT Reasoning Test, I took it three weeks ago. (About 25 years late, but that's another story.) I took an HP 49g+ to the test, but there were no problems for which I needed to do anything beyond basic arithmetic on it. I could have gotten by fine with pencil and paper, but then I might not have had time to both double-check all my answers and twiddle my thumbs for several minutes.

I did not take the SAT Subject Tests in Mathematics. From the test descriptions, it sounds like any scientific calculator should be adequate. You're not going to be asked to evaluate triple integrals or compute eigenvectors; there aren't any particular special functions of either the TI-89 or HP 50g that will give you a big edge.

If you're doing well in AP Calculus and have a little knowledge of basic statistics and probability, you should do fine on the math sections of the SAT Reasoning Test and on both of the SAT Subject Tests in mathematics. (And, for that matter, the quantitative part of the GRE, which I took this past August.)

Two years ago I took a linear algebra class for which the TI-85 or TI-86 were recommended. I was prepared to buy one if it proved necessary, but found that my HP 49g+ was more than adequate. The only drawback to not having the recommended calculator was that the professor would not have been able to show me how to solve problems on it, but I was able to work them all out myself without difficulty. Since the point of the class is to learn the math, not to learn the calculator, I'd claim that it doesn't make any difference which one you use, as long as you learn how to use it. So I wouldn't spend any money on buying yet another calculator of any sort, unless you decide that you're not satisfied with the TI-84+ and HP 50g. (Or unless you just want another cool toy.)

My personal opinion is that any of the 48/49/50 series of calculators are fantastic for math, science, and engineering, and that I would have a harder time with the TI-89. I bought a TI-92 some years back, and IIRC the TI-89 is basically a subset of that. I didn't find it to be nearly as convenient to solve calculus problems as the HPs. That may be due to my years of experience with RPL, ever since getting an HP-28C back in 1987.

The main advice I would give anyone taking the SAT Reasoning Test has nothing to do with the math portion. Rather, I'd make a suggestion about the essay. They give you a topic and only 25 minutes to write on it. DON'T do what I did. I spent about five minutes organizing my thoughts and selecting three main points to write about. Then I wrote an introduction and thesis statement, and paragraphs about two of my main points. Time was called before I could write about my third point and a conclusion.

While I followed the correct process for writing a good essay, it's completely wrong for the SAT! I only scored 8 of 12 points for it, which dragged my overall writing score down considerably. I've since seen that Dr. Les Perelman of M.I.T. has studied SAT essays and found a near perfect correlation between essay length and SAT score, without regard to any normal quality metrics for the essay: http://www.nytimes.com/2005/05/04/education/04education.html. This indicates that you should spend no time thinking, and all 25 minutes writing anything that pops into your head. Fill that paper up!

By comparison, I scored 5.5 out of 6 on the essays for the GRE, a test which has higher standards.

#17

For the AP test, you want to use whatever you're really good at using. As I recall, the calculator won't help you much except to get things done quicker than you can do in your head, or to check something that you weren't sure about. For both of those, you want speed. The level of mathematics on the AP isn't going to push either calculator too far.

Now that I think about it, the TI89 does pretty aggressive simplification, or converting your equation to some standard form, which often makes things more confusing. The HP typically gives a result closer to the form of the original equation (and therefor closer to whatever you did on your paper), and doesn't have so many of those crazy special functions that show up on the TI 89 (as I recall from before I sold my TI-89 to buy a HP-49g+)

For the SAT, it's pure speed. Use whatever you're fast with, where you know the keyboard well and you aren't going to make stupid mistakes.

That's my experience, at least.

-Jonathan

#18

The "best" calculator in this case is the one everyone else has. If they all have TI-89 then get the TI-89.

Also, I would not be switching to a new calc just before an important exam, that could be bad news.

Dave.

#19

Speaking completely outside the context of an impending exam, I can't really recommend the 89, strictly for usability reasons. As I'm sure you already know, the 89 is really nothing more than a 92+ in an 83+ shell (with slightly reduced screen size). This is all fine and dandy capability-wise; the machine can pretty much run circles around any other TI in terms of what it can handle.

The problem is that the OS was created well before transitioning to the smaller form factor, and the designers relied heavily on the notion that the user would have the full QWERTY keyboard available at all times. This resulted in a lot of useful math functions being buried in a less-than-ideal menu system, because they either had direct key equivalents, or could be very quickly typed out by name.

Now, move that onto a unit with drastically fewer keys, and a layout not optimized for letter entry (Why are X, Y, Z, and T ABOVE all the other letters?), and usage becomes quite a bit more cumbersome. You're either going to hunt-and-peck functions like factor() or expand(), or you'll have to become very accustomed to spending time with the cursor keys. It's either that, or build some huge custom menus yourself (it at least gives you that option).

Consider that the 92 already had three different shift keys to get everything done, and that the 89 now has four with the addition of the ALPHA key, and it's pretty obvious that reducing the number of physical keys probably wasn't the best way to go with that particular system. :)

Now, as for the 92+, or its replacement, the Voyage 200, I think they're both pretty fantastic, and if you're going to use a TI, then those (and the 86) are both excellent choices. Most stores don't have them on display, or even available in stock, but you can always try out an 89 to see what it does, realizing that entry is a good deal easier on its larger siblings.


#20

The 92, 92+, and Voyage 200 don't qualify under the SAT calculator policy due to the QWERTY keyboard.


#21

Yup, I know, hence the preface of "Speaking completely outside the context of an impending exam." :) Certainly worth pointing out, though. I seem to recall having been in a similar position back when I took the ACT. Can't remember if I opted for my TI-83 or HP 49g... Heh.

#22

Custom menus pretty much nullify your entire point. It took me about 15 minutes to pound out a custom menu script on my computer and transfer it over to the calculator.

I never have to use alpha or the catalog/math menus. I just use the function keys and 0-9 to select the function I want. There are plenty of reasons to use an HP over a TI, I just don't think this is one of them.


#23

I didn't say it was a reason to use an HP over a TI. I said it was a reason to use a TI-92 over a TI-89. I'd prefer the 92 any day! I'm not trying to start any brand loyalty debates here; there are fine machines from both manufacturers, and I own several from each.

#24

Unless you have a need for some specific feature in the 89, I don't see any reason for you to drop another hundred bucks on another calculator (Unless you can convince your parents to pay for it). I'm also currently in AP Calculus and am using the 50g that I bough last year for AP Stats when my 48gx proved too slow to punch in a bunch of data. It easily does everything we've learned so far and the answers are pretty and symbolic. Either should be able to do everything that comes up on the AP test.

As far as the SAT reasoning test, you barely need a calculator at all, as Eric mentioned. I did take the Math II subject test at the beginning of this month and there aren't really any calculus concepts on there. There's more calculus on the physics test, because they make you identify plots of velocity, acceleration, etc. given a plot of displacement or something along those lines. If you really understand your precalc and trig you'll do fine with any calculator. If you only sort of understood trig and precalc then a graphing calculator would help, but again, you don't need anything fancy. If I can offer you any advice for the math subject test, it's use whatever you are faster with. I only finished about the first 2/3 of my test, and had to leave the last chunk of questions blank. I somehow got an 800 still, which means that America as a whole must be pretty awful at math, since my friends who finished got a 670 and 710.

It probably just comes down to whatever you are faster with. I was lucky enough to start with a 41CV in 7th grade and I couldn't imagine using anything other than RPN now. If you were good with your TI-84, then you might like the TI-89, but I'd go to office max and try out one of the display models before shelling out the cash for one.

#25

I don't know if you need another calculator but I want to share with you my experience of using TI-89 Titanium screen. TI-89 Titanium is a very nice and powerful calculator (especially for students) but I found the screen dark and too small. And if I use a table lamp sometimes the shadows of characters are disturbing the reading. Except for that I like it. But I prefer my HP-50g.


#26

Buy them all. New calculators are cheap compared to the old classics.


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