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[Maths SL] Type II Logan's Logo

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This is my first portfolio and I am super stressed out because I have no idea where to start or what to do. My teacher gives us no help and its due in a couple of days. Please help!!!!

Edited by Sandwich
Edited title so this could become a new official thread for this portfolio.

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Your teacher isn't actually meant to give you any help with these portfolios - sadly they're a solo struggle! Anyway, we can give comments on what you think you're meant to be doing to help you along the way, but can't give you answers. We also can't give you either unless we know which portfolio you're talking about! If you check out the board, there are plenty of threads and I believe every single available portfolio ought to have a discussion topic where you can read what other members have asked/tried before, and also add your own questions. In order to avoid cluttering the forum, I'm locking this thread to confine all relevant conversation to the specific thread. :P

EDIT: Unlocked. This can be the new official thread :hug: If this is a brand new portfolio you may wish to give more information as to what exactly it's about, though, so people can help.

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It's not a brand new portfolio, however I've never heard anyone being set it before. If you'd like to ask specific questions we might be able to direct you towards the answer.

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yea ive tried all the search engines and they have been of no help.

Well the paper says: the diagram shows a square which is divided into three regions by two curves. The logo is the shaded region between the two curves. Logan wishes to develop mathematical functions that model these curves.

Identify and record a number of data points on the curves which will allow you to develop model functions. Define all variables used and state prameters.

Using technoology, plot these 2 sets of data points on a graph. What type of functions model the behaviour of the data? Explain why you chose these functions.

Find functions that represent the upper and lower curves forming the logo. Disscus any limitations.

Those are just some of the questions asked

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Well, those are the questions you have to answer. Are there any questions you'd like to ask us so that we can direct you to finding the right answer? What specifically is problematic, are you stuck in the very beginning, and why are you finding it difficult to move on?

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Well, those are the questions you have to answer. Are there any questions you'd like to ask us so that we can direct you to finding the right answer? What specifically is problematic, are you stuck in the very beginning, and why are you finding it difficult to move on?

Well I thought that i could find the points by transfering the logo onto a graph then using cubic regression to find an equation but i guess im stuck in writing it or wording it and what to do next.

Edited by 11054

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By cubic regression I'm supposing you're using your calculator to solve it. It's usually not advisable, the examiners want to see evidence of you doing mathematical work by hand. Technology is supposed to support and enhance the project, not solve it.

Wording it is just like writing a mathematical essay: First, I will use this equation to find...

Remember that you're supposed to write it in a way that a person who hasn't seen the task will understand what you are doing.

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Hi, I got this yesterday and it is due on Monday (7 days).

screenshot20091201at539.th.png

I took down 4 radom (x,y) coords (non were stationary points) from the lower curve of Logan's Logo and plugged them in this Gaussian Elimination Calculator and got the equation:

y = -(1/20)x^3 - (1/15)x^2 + (21/20)x - (14/15)

When I plugged the equation into my grapher in mac it did not draw a curve.

Is it possible to use Gaussian Elimination method with any (x,y) coords from a curve or do they have to be stationary points?

So far I have realized one way of finding the cubic equation of curve:

1. Take 4 coords.

2. Plug them into the a,b,c,d values of y = ax^3 + bx^2 + cx + d

3. Use Gaussian elimination method to find real values of a,b,c,d and voila I have a cubic equation for a curve.

Is this method mathematically correct or is there some flaw in it? Are there other methods for finding cubic equations of curves?

If I've crossed the line for revealing the answers then please let me know.

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I can't find any flaws in your method, but I can't give a definite correct or incorrect because I am not familiar with this portfolio.

Haboo

When I plugged the equation into my grapher in mac it did not draw a curve.

I don't really know why it wouldn't draw the curve, it might be in an odd window or it might be a problem with the mac grapher. The equation works fine on winplot and WZGrapher.

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Hi

I'm doing the Logan's logo and i chose to model both curves after sin functions. Most works ive seen on the internet chose to model one after sin and the other one after a cubic function. can my choice of function affect my grade?

I also had a question about parameters. What are they exactly?

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Hi

I'm doing the Logan's logo and i chose to model both curves after sin functions. Most works ive seen on the internet chose to model one after sin and the other one after a cubic function. can my choice of function affect my grade?

I also had a question about parameters. What are they exactly?

Well if the function isn't appropriate than of course it'll affect your grade - but otherwise I don't think it will as long as you justify it.

Parameters example within linear function:

y=mx+b

y and x are the variables, m and b are the parameters. They're the constants within a function.

Edited by masochist

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