Paul Jenkinson (Irvine, CA United States) gives the Texas Instruments TI-89 4,5 out of 5 stars
“After using a TI-83 Plus calculator for the last 5 years, I decided to upgrade to the TI-89 Titanium. This calculator is unbelievable in its features and power. First of all, it is more suited for advanced math, such as calculus and beyond. This calculator is NOT meant for high schoolers who are taking algebra, geometry or trig classes. If you don’t know what a derivative or an integral is, then save your money and buy a TI-84 instead. (Besides, I believe most high school math teachers ban the TI-89 on tests) This calculator can also run programs in its Flash memory, which can be downloaded from the TI website. A USB cable is included standard. TI has made the newly designed sliding cover much more secure than the old TI design (TI-83 plus, TI-86, TI-89 regular), whose sliding cover was not very secure and became looser over continued use. The cover is very hard to get off the first few times (I was almost afraid of breaking it off), but over time it has gotten easier. Switching over from the TI-83, the only problem I’ve encountered is the operation of this calculator is very different from the 83. The menus are different, the interface different, different buttons. It takes a while to get used to.”
Jenny McLeod (Dallas, TX USA) gives the Texas Instruments TI-89 4,5 out of 5 stars
“Prior to actually using this product, I wouldn’t have been able to imagine such a wealth of features being incorporated into a single hand-held device. It’s the most powerful calculator I’ve ever seen, and even 6 months after my initial purchase of it I still occasionally discover useful and shockingly-advanced functions I didn’t even realize it had.
For higher-level mathematics (undergraduate level calculus and beyond) it’s just too useful for words to describe. I’ve been using similar models all the way back to the TI-82 (that’s not a typo, I do mean the TI-82), and despite having become familiar with Texas Instruments’ powerful graphing calculators, the TI-89 still blew my mind.
The flipside of this truly impressive device is that it’s just overkill for basic applications. You just don’t need the incredible power of this calculator for anything but serious engineering or other fields that deal with advanced mathematics; if you’re not a science or engineering student, you may well be better off with a less costly and less complicated model. If, however, you have a use for such things as symbolic equation manipulation/solving and parametric/polar/differential/3D graphing (among an endless list of other capabilities), this is THE calculator for you.”
Bob Hailey (Vancouver, WA USA) gives the Texas Instruments TI-89 4,5 out of 5 stars
“Hi, I go to Clark College. I have passed every one of my math classes with an A. I am taking Calculus I, which is my fourth math class in college and part of my major, which is Paper Science and Engineering.
My teachers usually want students to bring their graphing calculators to class, so the students can learn and succeed. My teachers also show students how to use calculators to solve problems, so the students can get their things done efficiently. However, I’m not allowed to use my calculator on some questions on the tests, but I can get most questions answered correctly. Also, my teacher sometimes mark me down for only relying on the calculator to get the correct answers without showing my work. For example, in College Algebra during Spring term 2007, my teacher marked me down on one of the finding roots with imaginary numbers questions on my second test because I didn’t show my work, but I answered the question correctly.
With my calculator, I got a score of 100% on every one of my tests, including the final, in College Algebra. Also, in Trig, I aced every one of my tests, including the final. Therefore, I got an A in every one of my college level math classes.”
