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achiever123

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when ur loking for the quaratic and cubic function and when u find the new points according to the equation, there, im not able to get the last guide right for (8,149), im getting 146 for the quadratic equation and 147.2 for the cubic equation

Edited by dhruv
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Well you're trying to find the correct model to fit your data, and you're ultimately going to try lots and lots of models, so I wouldn't be surprised if those two don't fit your data points. Remember you're trying to solve a real-life problem in a mathematical way, and the method is trial and error, so you won't have 100% accuracy. In terms of a fishing rod, 147.2 isn't actually too far out for the line guides :P The whole idea is to find the correct equation, so you'll have to keep trying.

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  • 3 months later...

Hello guys! I'm in IB Math and I will admit I procrastinated and waited til the last minute to work on my portfolio! AHH!!! We are working on the Fishing Rods Portfolio. Has anyone out there had this particular one before? I needs some pointers on it because I really don't know how to begin. :P

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  • 2 weeks later...

HI

I have a portfolio due tomorrow. If anyone can please help me with this question with all of the problems. I need it badly. My teacher said there are no exceptions and this is worth 20% of my grade which is a lot. So please help. If possible can you please show me if you have already done the portfolio. Thank you.

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Although we understand that it is difficult and a right pain in the behind to do these maths portfolios, we do also understand that your grade for the portfolio has a large effect on your final grade at the end of the IB. As it's a piece of formally assessed work it's also your work! You have to figure it out yourself - we can help you by giving you advice on your work (if you read this thread through you should find plenty of tips to get you on your way) but we're not going to help you cheat.

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  • 2 months later...

Hi, I am have a little trouble solving the 8x8 matrix for the polynomial equation. Im not asking for any answers but simply for a little help. If someone could provide a different way of solving or an easier way to approach an 8x8 matrix please help. I really do not have the time of patience to solve it. Thanks in advance.

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Hi, I am have a little trouble solving the 8x8 matrix for the polynomial equation. Im not asking for any answers but simply for a little help. If someone could provide a different way of solving or an easier way to approach an 8x8 matrix please help. I really do not have the time of patience to solve it. Thanks in advance.

Use your calculator to solve it using the rref function.

Hi, I am have a little trouble solving the 8x8 matrix for the polynomial equation. Im not asking for any answers but simply for a little help. If someone could provide a different way of solving or an easier way to approach an 8x8 matrix please help. I really do not have the time of patience to solve it. Thanks in advance.

http://mathbits.com/Mathbits/TISection/Precalculus/matrices.htm

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  • 2 weeks later...

Hey,

So mine is due tomorrow, yet I'm not so stressed out as a lot of the people here...

Just that I've been reading through these posts and I've been slightly confused.

(The data points are the same as the other people have posted them [1,10][2,23] and so on)

1. It asks to find a quadratic and cubic function which model the situation.

Somewhere along the line of those thread it said, that one has to find the BEST model function? Is that so? I thought it was based on the principle of all of he functions work, when solving in the matrix sense, but some are better than others?

2. I've not plotted 0,0 neither does my x^7 pass through 0,0 is thát a limitation to it?

3. how many decimal places should i use? to 3. significant figures?

Thanks in advance

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Hey,

So mine is due tomorrow, yet I'm not so stressed out as a lot of the people here...

Just that I've been reading through these posts and I've been slightly confused.

(The data points are the same as the other people have posted them [1,10][2,23] and so on)

1. It asks to find a quadratic and cubic function which model the situation.

Somewhere along the line of those thread it said, that one has to find the BEST model function? Is that so? I thought it was based on the principle of all of he functions work, when solving in the matrix sense, but some are better than others?

2. I've not plotted 0,0 neither does my x^7 pass through 0,0 is thát a limitation to it?

3. how many decimal places should i use? to 3. significant figures?

Thanks in advance

1. Read down the question paper and you'll see you try out many different polynomial functions and then decide which of those is best, and then also try and find another (non-polynomial) function which also fits the data points well. As you say, one of the functions will work better than others.

2. The main theme of this coursework isn't actually the maths, despite the fact that's the most rubbish and time-consuming bit, but is in fact about the practical application of maths. Given that the whole point of you finding a function is because you're pretending to be a Master Artisan of Fishing Rods ( :S ) and need the function to help you make and design them, do you think having or not having (0,0) is a practical limitation? Remember you're modelling real life, and the relevance and application of the maths to real life needs to be the theme of your commentary throughout the coursework.

3. Again, this is something you have to discover yourself through the coursework and comment on if you want good marks. Do you think 3 s.f. is appropriate? If so, why? If not, why?

Most of the marks for reaching the high grades are to do with how well you consider the context of the coursework and make your maths fit around it :) Continually relate what you're doing back to the problem at hand and you're more likely to score highly.

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Again, this is something you have to discover yourself through the coursework and comment on if you want good marks. Do you think 3 s.f. is appropriate? If so, why? If not, why?

Most of the marks for reaching the high grades are to do with how well you consider the context of the coursework and make your maths fit around it :S Continually relate what you're doing back to the problem at hand and you're more likely to score highly.

Hey it has really helped me, I've changed a lot of my text so that it fits into the real world example :)

Just I'm still stuck with my s.f. ... more or less I'm done :)

Now its just a matter of a bit of fixing :)

So I'd really appreciate a little tip or something of the sort that could 'direct' me to what decimal place I should use...

My friend have been telling me everything...from the nearest cm, to leaving it at like 10 s.f. as the calculator tells me O_o

Anyways thxs for your previous help . . . really :)

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How to model your qaudratic and equation using GDC or any other math software capable of matrix operations:

1.) Consider general form of cubic and quadratic equations (where a,b,c,d are coefficients and where a is never zero):

y=ax2 +bx+c (quadratic)

y=ax3 +bx2 +cx+d (cubic)

2.) Insert points from the graph (x,y coordinates) into general from of the equation to get a system of equations (example):

4a+2b+c=7 (point 2,7 in quadratic equation)

9a+3b+c=8 (point 3,8 in quadratic equation)

16a+4b+c=5 (point 4,5 in quadratic equation)

Where did u get the numbers 4 9 16 from?

And what does "define suitable variables, discuss parameters/contraints" mean?

Being honest, I wouldn't use your calculator as it's a smart plan to plot the graphs of the functions and include them in your coursework. :)

Just enter in the points on Microsoft Excel or something and have it make a graph for you. Much easier too :)

I'm actually not sure how you'd get your calculator to do that, in any case!

Similarly, for working it all out (ie the equation you're after), it's perhaps easier to do it using matrices, rather than your calculator, as you can show all the steps of your working out. I recommend using www.bluebit.gr/matrix-calculator, as you can easily include print-outs from it to show your working and hit all the coursework marks.

Good luck!

I do not understand how to use the online matrix calculater..coud u please show me how to figur his out using the following values:

guide numb. 1 through 8

Distance from tip: 10 23 38 55 74 96 120 149

Im working on fishing rod math portfolio,

And im supposed to use a matrix to find a quadratic function and cubic function

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  • 2 weeks later...

can someone tell me what it means by suitable variables and parameters/constraints are?

constraints are basically your limits. Like since the rod is 230cm long, it can't be longer. That's a constraint

Your guides can only be whole positive numbers between 1-9. Constraint

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Similarly, for working it all out (ie the equation you're after), it's perhaps easier to do it using matrices, rather than your calculator, as you can show all the steps of your working out. I recommend using www.bluebit.gr/matrix-calculator, as you can easily include print-outs from it to show your working and hit all the coursework marks.

Good luck!

{quote}

When using the online matrix calculator

I put in my x and y values what do i do next to get the quadratic formula?

:)

Honestly you can't think you'll get full marks by just using regression on your calculator.

Hi, i need help using the online matrix calculater

I need to find a polynomial function...

1 1 1 1 1 10

16 8 4 2 1 23

81 27 9 3 1 38

256 64 16 4 1 55

625 125 25 5 1 74

Please explain rref, and how to into this matrix into rref on the online matrix calculator.

Edited by Mahuta ♥
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