# Growth and Decay Functions?

1. Oct 6, 2004

### Poweranimals

Does anyone know how to use the growth and decay functions? How would any of these be useful in everyday life?

2. Oct 6, 2004

### arildno

What do YOU mean with "growth and decay" functions?

3. Oct 6, 2004

### Gokul43201

Staff Emeritus
Are you refering to exponential growth and decay ?

4. Oct 6, 2004

### Gokul43201

Staff Emeritus
Also, what do you mean by "everyday life" ? My everyday life involves doing physics, so yes, such functions are useful in my everyday life.

5. Oct 6, 2004

### Poweranimals

Yeah. Sorry for not specifying.

6. Oct 6, 2004

### Gokul43201

Staff Emeritus
Is this homework ? I can't imagine that someone would ask you a question like this !

Not only is it ill-defined, it serve any purpose to have someone answer such a question.

If you have a more specific question, ask it.

7. Oct 6, 2004

### Poweranimals

This is the Homework helpzone, isn't it? Here is the question: Can you think of a growth or decay function that you encounter in your work or in your personal life? It's for a report I'm doing for College Math. I don't really have anything to go on at the moment.

8. Oct 6, 2004

### arildno

Try to look into how banks calculate interests on your money.
Is that "useful" enough?

9. Oct 6, 2004

### Poweranimals

Maybe if I had a better understanding how the functions work, it'd be more helpful.

10. Oct 6, 2004

### Gokul43201

Staff Emeritus
Simply put, an exponential growth is seen by anything that grows are a steady rate, say, 5% per year, for example.

(Yes, it might seem counter-intuitive that steady and exponential growth are the same thing.)

Exponenetial decay is seen in chemical reactions, radioactivity, electronic circuits, etc. Look these up to see how they apply.

Here are the formulas that describe these :

Growth : $A = A_0 r^{(t/T)} + B_0$

Decay : $A = A_0 r^{-(t/T)} + B_0$

11. Oct 6, 2004

### vsage

In ideal problems (such as uninhibited population growth) can be modeled by exponential functions as well as interest, the decay of atoms per mol of a substance at a certain time or the concentration of a solution that contains an initial concentration but has flowing water through it. They're all pretty ideal though just to stress that.