# Recursive and Explicit Equations...How to Write Them?

• Feb 10th 2009, 04:53 PM
milkyway4679
Recursive and Explicit Equations...How to Write Them?
Hi,

I have been struggling with understanding these equations, searching for a way to simplify them. My professor makes them seem impossible, and I don't understand her teaching methods...so going to her for help, isn't really an option. I have been researching for a different way to do them, but I just cannot figure it out. Help!!

Here is a problem I am working on...if you could give me an example of something similar (I would rather find the answer to this one on my own!(Happy)).

Suppose that a population grows according to a linear growth model. The initial population is 200, and it grows by 25 every month.
--Write a recursive equation that can be used to find the population at the end of any month.
--Write an explicit equation that can be used to find the population at the end of any month.

A recursive formula is going to define a future term by previous ones. Something like $x_{n+1}=x_{n}+x_{n-1}$. That's the Fibonacci sequence. It relies though on knowing previous terms explicitly.