TI-83 plus graphing calculator help

[tinyboy21]

How do you find the vertex of a parabola using the calculator?

[Dave]

Personally, I would plot it and observe where the point is

[tinyboy21]

sure

[ydoaPs]

find where the first derivative = 0. i think you may have seen it as -b\2.

[Dave]

Doesn't really help much if the person in question hasn't touched differentiation

 

As I said, plotting it will show you where the minimum point is. The other (slighty more) mathematical way of doing it is to work out where a line of zero tangent intersects the curve. And, of course, there's calculus if you've done that kind of thing already.

[Cap'n Refsmmat]

Hit 2nd TRACE. If the parabola's vertex is at the bottom, hit "minimum" and if it's at the top, hit "maximum."

Now it will ask you for a left bound. Arrow over to the left of the vertex and hit enter. Now it asks you for right bound; move to the right of the vertex and hit enter. When it asks for a guess, just hit enter where you think the vertex is.

Voila, it spouts out the vertex.

[tinyboy21]

alright, thanks all.