- KJ4UTS

Determine whether a linear, quadratic, cubic or quartic polynomial best fits the data.

- katieb

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- KJ4UTS

##### 1 Attachment

- KJ4UTS

|dw:1444327099717:dw|

- KJ4UTS

When I graphed in on my calculator I got this and I think that is cubic?

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- KJ4UTS

##### 1 Attachment

- KJ4UTS

|dw:1444327237346:dw|

- KJ4UTS

This is what I got for the second problem when I graphed it on my calculator and I think its cubic also but am not sure?

- freckles

It seems like a cubic would best fit the data...
however this one looks more cubic http://www.wolframalpha.com/input/?i=plot+%280%2C32%29%2C%284%2C45%29%2C%288%2C36%29%2C%2812%2C31%29%2C%2816%2C24%29%2C%2820%2C29%29
then this one
http://www.wolframalpha.com/input/?i=plot+points+%281965%2C98%29%2C%281970%2C86%29%2C%281975%2C58%29%2C%281980%2C24%29%2C%281985%2C34%29%2C%281990%2C46%29
a quadratic might even do for this graph

- freckles

is there any methods you look at besides just plotting points?

- KJ4UTS

No is there other methods to determine what they are?

- KJ4UTS

|dw:1444328445790:dw|

- freckles

well there is polynomial least squares thingy
http://www.wolframalpha.com/input/?i=least+squares+%281965%2C98%29%2C%281970%2C86%29%2C%281975%2C58%29%2C%281980%2C24%29%2C%281985%2C34%29%2C%281990%2C46%29
this method come up with a 4th deg polynomial

- freckles

wait no sorry misread

- freckles

it look like it come up with three options for best fit

- freckles

either a quartic or cubic or a quadratic for that one

- KJ4UTS

I thought quadratic was like what I drew above?

- freckles

it could also be upside down

- freckles

hey

- freckles

look at the graphs in that picture

- freckles

against the points we were to plot

- freckles

it likes the blue curve is closest

- freckles

which is the quartic

- KJ4UTS

So the first one is cubic and the second one quartic?

- freckles

both according to the graphs there are quartic
though for that one cubic is a close second
if you try the same coding I typed in earlier into wolfram
though you should probably use the methods that were talked about in your class
whatever methods those were

- freckles

is it just plotting points a method in your class? or are there others?

- KJ4UTS

I learning about polynomial regression this unit and we primarily use the ti-84 for this which is what I was shown

- freckles

if you guys are just plotting points, it seems very opinion like to me...
|dw:1444329367542:dw|
because to me this kinda makes me think of quadratic

- freckles

|dw:1444329423580:dw|

- freckles

but if we wanted to get a better graph we would go with the quartic

- freckles

to best fit the points

- freckles

@Loser66 what do you think

- freckles

http://www.wolframalpha.com/input/?i=plot+points+%281965%2C98%29%2C%281970%2C86%29%2C%281975%2C58%29%2C%281980%2C24%29%2C%281985%2C34%29%2C%281990%2C46%29
http://www.wolframalpha.com/input/?i=plot+%280%2C32%29%2C%284%2C45%29%2C%288%2C36%29%2C%2812%2C31%29%2C%2816%2C24%29%2C%2820%2C29%29
we are just suppose to plot these points
and just guess what graph best fits
(we don't need least squares method or whatever)

- freckles

|dw:1444329561722:dw|
I would agree this makes me think of a cubic because of ...

- freckles

|dw:1444329593289:dw|

- freckles

but like I said quartic would be even better as the graphs in wolfram suggested

- KJ4UTS

@freckles so you think that the first one is cubic like I thought but what do you think the second one is?

- freckles

I thought the first one look like this:
|dw:1444329869071:dw|
and the second one look like this:
|dw:1444329880021:dw|

- freckles

the first one reminds me of a cubic
and the second one reminds of a quadratic

- freckles

but I could be wrong

- KJ4UTS

Ok thanks, my drawings at the top did not exactly represent what I got on my calculator it was just a general sketch.

- freckles

I don't like the these two questions if you couldn't tell

- KJ4UTS

Yeah I could tell lol me neither

- freckles

It seems to be opinion based if you guys are really just plotting points as a method

- freckles

I mean we definitely wouldn't say a line

- KJ4UTS

Yeah that's for sure its just been confusing to me

- freckles

good luck
let me know if you get the questions right

- KJ4UTS

ok thanks

- KJ4UTS

@peachpi what do you think

- freckles

or @ganeshie8

- anonymous

I agree with @freckles the first one looks cubic, the second looks quadratic

- KJ4UTS

Ok thank you :)

- KJ4UTS

@freckles The first one is cubic but the second one was not quadratic do you think it was quartic?

- freckles

do you think my guess is really going to be better than yours? :p

- freckles

maybe you were right to think they were both cubics in the beginning
that was your first guess
sometimes are first guess is the right guess

- KJ4UTS

oh ok maybe but I thank you for taking the time to help me :)

- freckles

i'm sorry I wasn't better at the guessing part :p

- freckles

- freckles

|dw:1444331902570:dw|
they were suppose to plot points
I thought the polynomial that best fit this was a quadratic
what do you think?
(also quadratic was marked wrong)

- freckles

they had other options
like linear, cubic, quartic, none of these
we already can throw out linear
so it is either cubic or quartic or neither

- KJ4UTS

I was looking at some other graphs and it looks like it could very well be quartic is that what wolf math said?

- freckles

well wolfram said that quartric would be a good fit for both
so it makes me worry since that one question accepted cubic

- KJ4UTS

I see what you mean, this question is such a nightmare lol

- freckles

quartic is my final guess
I'm done
it could be wrong just so you know

- freckles

well hey before you click it

- freckles

lol so you are just suppose to put those points in the calculator and that is it right?

- freckles

like you don't have to click in other things
just look at the graph right?

- KJ4UTS

pretty much

- freckles

well that sucks

- KJ4UTS

Yeah I will let you know I have two more times to answer this

- KJ4UTS

or to re answer I should say and if its not quartic we will try cubic and get to the bottom of this :)

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