Solve Cubic Regression Equation for US Limousine Production

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Cubic Regression

Homework Statement


(I was given a graph to enter into my calculator):

Let x represent time(in years) since 1980, and let y represent the corresponding U.S production of limousines. Enter the data in a graphing utility and find a cubic regression equation for the data.

Homework Equations


Calculator steps
Stat ---> Calc --->CubicReg... now what

The Attempt at a Solution


I have found the Cubic Regression equation but have forgotten how to make the equation itself appear in the y equals screen so that I can see the graph. I need that to answer the next part of the question.

I believe it should look something like this, but I'm not sure exactly how:

CubicReg L1,Y1,L2

Any help is greatly appreciated!
 
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What kind of calculator do you have?
 
calculator

im using a TI-83 Plus
 
I have a TI-89, but this .pdf file may help you out.

http://academic.pg.cc.md.us/psc/TI83_booklet.pdf

Page 5 tells you how to enter data in list form. In your case, list 1 would be x = years since 1980 = 0, 1, 2, 3, ...
List 2 would be y variables and the entries would be the number of limousines that correspond to the year in the x column. Ex. In year 1980 (x=0), y = 100000 limousines
were produced.

Page 6-7 tell you how to select cubic regression from the STAT menu and enter the lists (L1, L2) that you want to analyze.

I wish I knew more about the TI-83, but hopefully you can find enough info in the pdf to do the problem.
 
thank you

thank you very much, I'm sure that will help. I'll go go check it out right now.
 
Thank You

THANK YOU! You area lifesaver, thank you for taking a little bit of time out of your day to save my whole night!
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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