I am a first year Petroleum Engineering student and I currently use a TI 83+. However, the TI 89 comes recommended from my math professor and TA. I have two questions: 1. Should I get one? It is that much more useful? How so? Pros and cons? 2. Should I get a TI 89 or a TI 89 Titanium? I've used 84's and I dislike their bulkiness and their buttons, so I lean towards the TI 89 which uses the same styling as the 83. What about performance differences? I hear that the regular 89 lacks some kind of root ability.