Question 1067007: I need help please!
Use technology to find the quadratic regression curve through the given points. HINT [See Example 5.] (Round all coefficients to four decimal places.)
{(0, 1), (-2, 7), (-4, 4)}
y(x)=
Im so confused please help
Answer by KMST(5328)   (Show Source):
You can put this solution on YOUR website! "Example 5" may give you a clue that I do not have.
Not having your textbook, or class notes (and not knowing your teacher/instructor),
I can only guess what answer is expected. My guess would be as follows.
I would use Microsoft Excel
(because that is the technology I have handy).
I assume you have Microsoft Office or at least Excel in your computer.
I would enter the x values (0,-2,-4) on column A,
and the y value corresponding to each x to its right, on column B.
Unfortunately, software like Excel is continuously updated,
so that you may encounter different versions on different computers.
The commands needed and the way results are displayed
change a little from one version to the next.
In my version of Excel,
I have to click on the Insert tab,
to be able to graph the regression curve.
I can do that before or after
selecting (highlighting) the data I had entered.
Then, with the data highlighted,
I would select "scatter" as my chart type choice,
and the graph choice with only points (no line).
A graph with the points plotted would appear.
Right-clicking on one of the points on that graph,
would make a menu pop up,
and I would click on "Add Trendline".
That would make another menu window pop up,
where I would select "Polynomial" with order 2,
and "Display Equation on chart",
before hitting "close."
Right-clicking on the equation that appears on the graph,
I would select "Format Trendline Label",
and then four the option number kon the left side),
I would choose "Number" and 4 decimal places,
before hitting close.
The equation on the graph would read
 ,
and that is the answer I guess would be expected.
NOTE 1: Excel is not the only technology available,
and in your class another kind of software,
or maybe a graphing calculator could be the technology
that you were expected to use.
NOTE 2: Technology is not needed for this particular problem,
because the curve represents scented by that equation
passes exactly through those three points.
Just like two points determine a line,
Three points determine a quadratic function.
So, you could have
written  and
substituted the coordinates of the three points,
to get a system of 3 linear equations on a, b, and c,
whose solution would give you the answer.
If you had been given more than three points,
It could be that no quadratic line would go through all points.
Then, technology would be the best way to find the
"best fit" regression curve.
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