How do I find the coordinates of a vertex using a TI-83 graphing calculator?

Answer 1

On the graphing screen, the function key for MATH should have choices including MIN and MAX. By inspection, you'll know which one applies to your vertex. So select the appropriate one and set the lower bound (to the left of the vertex) and the upper bound (to the right of the vertex), and it will return the coordinates of the vertex.

Answer 2

You can graph it. Then find the maximum or minimum.