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Topic: What would you do if you had TI-92's?
Replies: 3   Last Post: Feb 22, 1998 7:58 PM

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 Chris & Sheila King Posts: 484 Registered: 12/6/04
What would you do if you had TI-92's?
Posted: Feb 18, 1998 12:13 AM

This is prompted by an e-mail that I received.

I mentioned that our math dept. had just purchased 20 TI-92's plus a
viewer. These are supposed to be for all math teachers in our dept. to
use. I most easily can envision the geometry teachers (of which I am
one) using the Cabri/Geometer's Sketchpad like application. (I also have
and have taken my Geometry class in about 4 or 5 times so far this
school year.)

But, for Calculus...what would one use the TI-92 for?

I wanted to use them to "discover" the chain rule, but we didn't get the
calculators until we were long past that. I thought, I could have the
students use the symbolic manipulation part to help with the following
problem:
Given:
f(x) = sqrt(x^2-2x)
g(x) = sqrt(x)
h(x) = x^2-2x

First, express f(x) as a composition of g(x) and h(x).
Second, find f'(x), g'(x) and h'(x). Express f'(x) in terms of g, h, and
their derivatives. [ the TI-92 I envisioned being used for finding
f'(x). I did have my students do this without the TI-92. They had to use
the definition of the derivative to find f'(x) since we didn't have the
chain rule yet, and were trying to discover it.)

I only assigned them a very few problems of this type over a few days.
With the TI-92 they could do the derivative of f(x) on the Calculator,
and many more such examples without the tedium of cranking through the
definition of the derivative and hopefully begin to recognize the
pattern themselves.

Of course, my students all own their own TI-82 or -83. So, I would like
to use the 92's for something they can't do on their 82s or 83s. To me,
that means symbolic manipulation or things with the Geometry
construction application. I have some ideas that it might be useful with
constructing tangents that one can drag and maintain the tangency, but I
haven't had enough time to try that out yet and see how it works.
Anyhow, we're long past that, too (for this year).

Here is a call for all ideas that you might have for using the TI-92s to
teach AP Calculus.

Sheila King

Date Subject Author
2/18/98 Chris & Sheila King
2/20/98 NDianese@aol.com
2/22/98 Charlie Bodine
2/22/98 Dave Slomer