[NABS-L] Finding Zeros on a TI84+

[Julia LaGrand]

Hello,
  My name is Julia LaGrand and I am a junior in high school taking AP Calculus ABOUT. I use a TI84+ calculator from APH, with the Orion extension. I am currently struggling with optimization problems and finding zeros of the second derivative. In the past, whenever I have needed to find zeros, I use the table function on the calculator, since my understanding is that the calculator needs some help with moving the cursor that requires a visual sense of the graph. Is this true? If so, how do you all find zeros when the table can only go in relatively large increments and often the answers to these questions are extremely long decimals (having the calculator go by thirds has always worked for me in the past). If not, how do you guys find the zeros of the function with the Orion?
Thank you so much for your help!
Julia LaGrand