# Homework Help: Exponential into polynomial

1. Jul 20, 2010

### darthxepher

1. The problem statement, all variables and given/known data

Turn y = y(0) * e^(-kt) into a polynomial.

2. Relevant equations

3. The attempt at a solution

I have no idea of how I would go about doing this. I know you can use taylor series to approximate it, but is there any other way?

Thanks,

Darthxepher

2. Jul 20, 2010

### lanedance

3. Jul 20, 2010

### Dick

Well, no. exp(-kt) isn't a finite degree polynomial in t. You can only approximate it with polynomials. There are other approximations besides taylor series, but I'm not really sure what you are asking.

4. Jul 20, 2010

### darthxepher

The assignment is to find some value of k given some information, but the assignment wants us to convert that expression into a polynomial then solve for k. Does that make sense?

5. Jul 20, 2010

### vela

Staff Emeritus
Take the log of both sides of the equation.

6. Jul 21, 2010

### darthxepher

Ya i did that, then solved for k but that still doesn't give me a polynomial... :P

7. Jul 21, 2010

### HallsofIvy

then perhaps you should tell us what the problem really is- what the "some information" that is given?