# IA Type I - Lacsap's Fractions

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Hi everyone,

I am given the portfolio assignment and thankfully it isn't that hard. But, I have trouble explaining it. By looking at the numbers, I've noticed that the numerator increases by 1 than the previous number. What I meant is, in the 3rd row the numerator is 6 and it increases by four and becomes 10 in the next one. Then, 10 increases by five and becomes 15 in the 5th row. However, it seems to me that my explanation is sort of awkward. So I decided to ask you guys how you would explain it.

I am attaching the portfolio method. Thanks in advance for your help! =)

1.pdf

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Hi again!

Sorry I am late to reply! I read your PM yesterday but have just got time to have a look at this task now.

Firstly, is this the new task (for 2013) or an old one for your practice?

Qn 1 says five rows but there are only 4 rows btw I'm guessing the first row is 1 though.

Ok so as you notice, the numerators are 1, 3, 6, 10 and 15 on the 1st, 2nd, 3rd, 4th and 5th line respectively. I suggest the graphical method: plotting n (row number) against the numerator then find the best fit curve. You can talk about the differences in each term too.

Good luck!

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Hi everyone,

I am given the portfolio assignment and thankfully it isn't that hard. But, I have trouble explaining it. By looking at the numbers, I've noticed that the numerator increases by 1 than the previous number. What I meant is, in the 3rd row the numerator is 6 and it increases by four and becomes 10 in the next one. Then, 10 increases by five and becomes 15 in the 5th row. However, it seems to me that my explanation is sort of awkward. So I decided to ask you guys how you would explain it.

I am attaching the portfolio method. Thanks in advance for your help! =)

I've had this assignment too. For the general statement of the numerator and row number relationship I got a(n)=n(n+1) / 2 . I put it in the graphing calculator under STAT, and calculated the quad. regression.

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I have also attained the same assignment and my biggest concern is how to figure out the general statement for the denominator

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so this is the new task yeah? I want a copy of the full 2013 portfolios anyway...

I have also attained the same assignment and my biggest concern is how to figure out the general statement for the denominator

Always try to make a sequence first. Look at qn 5,

Let En( r ) be the (r+1)th elementh of the nth row, starting with r=0.

En(1): 1, 2, 4, 7, 11

En(2): 4, 6, 9

Don't you see any pattern there...?

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I am also having a heap of trouble finding the denominator. I see the pattern, but I cannot come to a general statement.

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Can anybody get me the full new IA tasks PDF?

I am also having a heap of trouble finding the denominator. I see the pattern, but I cannot come to a general statement.

Read post #5, in case if you missed it. After that try to express the thing in terms of r and n. Looks complicated but I'm sure once you get it you'll know the general statement!

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I read post five, but am still having huge troubles with it :/.

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but we are not here to give you answers... we can hint you to the right direction only to a certain extent.

try the graphical method if you still can't form the GS with some algebra.

don't you notice what actually the difference in each term is??

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What is the graphical method?

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This is going to be a "oh hey, how did I miss that?" moment

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R would be the term number right? and N is the row number?

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Yes. I read the task and needs to be the row number.

Edited by Drake Glau

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Is there any direction you could lead me to?

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If I follow the "En(1): 1, 2, 4, 7, 11

En(2): 4, 6, 9"

The rest of En(2) would be 13 and 18?

I can't seem to figure out En(3).

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What is the graphical method?

Plot En(1) against n Plot the denominator of En(1) against n and find best fit...

Do the same to En(2) etc

R would be the term number right? and N is the row number?

Quite tricky, yes n is row number. (r+1) is the term number given that r>=0.

If I follow the "En(1): 1, 2, 4, 7, 11

En(2): 4, 6, 9"

The rest of En(2) would be 13 and 18?

I can't seem to figure out En(3).

Yes yes exactly!! umm idk how to point this out in words but look at the denominator from the right side of the triangle, the differences in the denominators of the 2 terms before 1 are always 2. the next diff is 3 and the next one is 4. I hope you get what I mean.

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YES! I am understanding now, but what do you mean by "the differences in the denominators of the 2 terms before 1 are always 2" what are the denominators of the 2 terms before 1?

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Yeah, I get you. It's just gonna be hard for me to explain it in words. But if I am getting you, then after the row with "15/11" would be

1 21/16 21/13 21/? 21/13 21/16 1 right?

What could be the middle number??

Edited by Trikey

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so this is the new task yeah? I want a copy of the full 2013 portfolios anyway...

I have also attained the same assignment and my biggest concern is how to figure out the general statement for the denominator

Always try to make a sequence first. Look at qn 5,

Let En( r ) be the (r+1)th elementh of the nth row, starting with r=0.

En(1): 1, 2, 4, 7, 11

En(2): 4, 6, 9

Don't you see any pattern there...?

Thank you very much I have figured it out now!

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What is meant by stating "plot En(1) against n"...what is 'against n' referring to?

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