Geometry curriculum question- exponential and decay functions

Discussion in 'Secondary Education' started by chessimprov, May 23, 2010.

1. chessimprovRookie

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May 23, 2010

Should I be showing formulas like y = a(1+r)^ t when going over exponential and decay functions? It does not seem so because I do not find it in any Geometry book I haver so far. Seems like more of a pre-calc thing. Not that I do not want to enrich them, but there seems to be more than enough material to try to cover anyway.

3. AliceaccMultitudinous

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May 23, 2010

My sophs haven't seen exponential functions yet, so it would be too much of a stretch.

We teach that in Precalc.

4. MuttlingDevotee

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May 23, 2010

We introduce exponential growth/decay in Algebra I and again in Algebra II.

If you're asked to teach it in geometry (which there is a lot of algebra in geometry), I would certainly present the equations behind the graph.

On a side note, this is my favorite subject to teach and it is very easy to teach with real world examples such as....

Growth of Savings Account/Retirement Account Interest
Decay of Drug Concentrations in the Body
Decay of Car Values
Growth of the U.S. National Debt
Growth of Bacterial Cells
etc

5. chessimprovRookie

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May 23, 2010

y = a(1+r)^ t
is actually more related to geometric sequences. But I still don't think I learned these formulas until pre-calc. I don't have much to work with in terms of state standards except for this TechPaths website and whatever objectives are mentioned on the online textbook, EPIC. So, it's very confusing and I have to keep constantly making judgment calls.

6. MuttlingDevotee

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May 23, 2010

y = a(1+r)^ t

Technically speaking, that is the compound interest equation. a is the starting amount, r is the interest rate and t is the number of compounding periods.

You are quite correct in that this is a judgement call. I wish you well.