Quandaries
and Queries 

I now understand exactly
what I have to do but I am having trouble finding a formula for something.
I need to find a formula that will work with any number.
I can't seem to find a formula that will work with any number. Any help
would be much appreciated. Jenny 

Hi Jenny, Since the third difference is a constant the n^{th} term is a cubic in n. That is
for some a, b, c and d. You can use the fact that you know x_{0}, x_{1}, x_{2}, x_{3} and x_{4} to set up a system of four linear equations for a, b, c and d. When I did it I found
Penny


