Converting Exponential Decay to Polynomial: Solving for Y(0) and k

In summary, the conversation is discussing how to turn the exponential function y = y(0) * e^(-kt) into a polynomial for a given value of k. The suggested approach is to use the Taylor series or other approximation methods. However, the initial poster is unsure of how to proceed and is seeking clarification on the problem.
  • #1
darthxepher
56
0

Homework Statement



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


Homework Equations





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
 
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  • #3
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
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
Take the log of both sides of the equation.
 
  • #6
Ya i did that, then solved for k but that still doesn't give me a polynomial... :P
 
  • #7
then perhaps you should tell us what the problem really is- what the "some information" that is given?
 

1. What is an exponential function?

An exponential function is a mathematical function in the form of f(x) = ab^x, where a and b are constants and x is the variable. The value of b is called the base, and it is usually a positive number greater than 1. The variable x can be any real number, and the function produces an output that is equal to a multiplied by b raised to the power of x.

2. How does an exponential function differ from a polynomial function?

The main difference between an exponential function and a polynomial function is the variable's placement. In an exponential function, the variable is in the exponent, whereas in a polynomial function, the variable is in the base. Additionally, the exponent in an exponential function can be any real number, but in a polynomial function, it is limited to whole numbers.

3. Can an exponential function be converted into a polynomial function?

Yes, it is possible to convert an exponential function into a polynomial function. This process is called taking the logarithm, and it involves finding the inverse function of the exponential function. The resulting function will be a logarithmic function, which can then be rewritten in exponential form to get a polynomial function.

4. What are the applications of exponential functions?

Exponential functions are commonly used in various fields, including finance, biology, physics, and economics. In finance, they are used to calculate compound interest and growth rates. In biology, they describe population growth and decay. In physics, they model radioactive decay and other natural phenomena. In economics, they are used to model supply and demand curves.

5. Are there any real-life examples of exponential into polynomial conversions?

Yes, there are several real-life examples of exponential into polynomial conversions. One example is the conversion of the pH scale, which measures the acidity or basicity of a substance. The pH scale is based on the logarithmic function, but it is often converted into a polynomial function for ease of use. Another example is the Richter scale, which measures the intensity of earthquakes. It is also based on a logarithmic function but is commonly converted into a polynomial function for practical purposes.

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