Finding and storing intercepts

[veeqdee]

I have a TI-89 Titanium and I need to be able to find the intercepts or zeros of two equations, and store the exact x-coordinate. My AP Calc test is in May and I urgently need to know how to do this before then.

I've tried this on a TI-83 and 84, and they both work fine. But my TI-89 won't let me store the x-coordinate.

1. I enter in the equations on the y= screen. (e.g: x^2 + 4 and e^x)
2. I press Graph.
3. I press Math >> Intersection.
4. From here I can tell that the intersection is about 1.05801.

The problem at this point is that I can't store this number, and I can't see any more digits. If I press Store, both the x and y coordinates at the bottom of the screen disappear. If I press Enter, the same thing happens. Pressing the arrow keys just moves the cursor.

I've been trying to figure this out all year! Am I missing something completely obvious? Is there another way to get the exact interception point? Please help.

[RAH]

I have the exact same problem. How do I do this ?

[veeqdee]

I took the test last year and this is how I eventually solved my problem:

Say you want to find the intersection of:
y = x^2
y = x

1. Press Home.
2. Go to [F2] (Algebra) then 1:solve(
3. Enter in "solve(x^2=x,x)".
3a. If you already have your equations stored in the Y= editor, you can use that instead. e.g. "solve(y1(x)=y2(x),x)"
4. The answer will come up with x=0 or x=1.
5. Remove the part you don't need.
6. Press [Sto] (your variable).

This will give you the intersection points for x. If you need the y-coordinate, plug your answer back into either equation.

It requires some extra work, so it's not perfect, but it allowed me to pass the AP exam. Good luck.