# IA Infinite surds

## Recommended Posts

My IA is on infinite surds and I have a few questionss..

I don't know how many sig figs to pick.. is there a specific rule??

Please heelp! Mine is due in two days!

##### Share on other sites

I think it's in the rules to ask questions here, right?

I've got mine on the same thing

for sig figs, I did up to 9(as far as the graphing calculator would allow), and you'll see why after!

if you have a good program use as many sig figs as you can, but I think nine is good for the start=P

edit: whoops didn't see the timestamp!

Edited by A_Mai

##### Share on other sites

I got my IA on infinite surds too! I have no idea what that is either.

I think I would also need some help on figuring out what to do also. This portfolio assignment was given to us on the forth day of school and is due after a week. Has anyone else received their portfolio assignment so early in the year?

I feel like I would not be able to give a thorough and exemplary effort because I don't know how to approach the problem so early in the year. Ahhhh!

Can someone explain the principle of what an infinite surd is? And also how to solve it when it is replaced by a recurring variable (i.e. square root of k + square root of of k + ...)? To find the sum would you just use the equation for finding the sum of an infinite series?

##### Share on other sites

Can the value of an infinite surd be zero? Can it be one?

Edited by Tilia

##### Share on other sites

If I have understood correctly the question:

The limit is:

Is always one, you only have to study two cases. When 0<a<1, and when 1<a. And you will see it.

##### Share on other sites
If I have understood correctly the question:

The limit is:

Is always one, you only have to study two cases. When 0<a<1, and when 1<a. And you will see it.

That is definitely beyond my maths knowledge so far. I was speaking about that infinite surd portfolio, which I guess other people in here are doing/have done as well. Anyway, I'll figure it out somehow.

##### Share on other sites

[Considering the infinite surd as sqrt(k+sqrt(k+...))]

Experimentally, I've found that if you take k=n²-n, the infinite surd value will be n. (except for n=1)

(i.e. n=[1+sqrt(4k+1)]/2) (you have to prove it)

Therefore:

- If you are considering k in N*, the infinite surd value will be higher than (or equal to) phi.

- If you are considering k in N, the infinite surd value for k=0 will be 0.

- If you are considering k in R, the infinite surd value can be 0 if k=0, but it can't be exactly 1. If you take k=0,000...(m zeros)...0001000...(m zeros)...0001, the infinite surd value will be 1,000...(m zeros)...0001. So, you can obtain values as close to 1 as you want, but it will never be 1.

Edited by GNRS
• 1

##### Share on other sites

I just got the assignment today. Ha wish me luck.

##### Share on other sites

GAWG THIS ASSIGNMENT IS SOOOO HARD Dx

anyone got any advice on doing this stuff....

A1 = √1+√1+√1……..

> Formula for an+1 in terms of an

##### Share on other sites

I did this portfolio, and I'd recommend you to keep as many decimal places as you can.

(P.S. I used Excel to get more decimal places than the GDC could allow for)

This is because of the whole idea of a limit... more decimal places help you understand what is happening with your surds a lttle bit better

Edited by 1-2-3

##### Share on other sites

thanks for the advice.. but i just got this assignment so most of the stuff you just told me i didn't understand..

besides the keeping as the most decimal places as i can...

btw... did you get like a math program to do the SURDS?????

______or do you just use word and excel?

##### Share on other sites
thanks for the advice.. but i just got this assignment so most of the stuff you just told me i didn't understand..

besides the keeping as the most decimal places as i can...

btw... did you get like a math program to do the SURDS?????

______or do you just use word and excel?

I think for the initial stages, you're just supposed to calculate the value of the whole surd for when k=1, k=2, etc. and put them in a table... correct?

You can either do it using a normal calculator or you can use Excel.

Then, I think it says you have to graph it.

The graphing can be done using the GDC, Excel, Graphmatica or Graph.

I like the last 3 better than the GDC.

##### Share on other sites
I think for the initial stages, you're just supposed to calculate the value of the whole surd for when k=1, k=2, etc. and put them in a table... correct?

You can either do it using a normal calculator or you can use Excel.

Then, I think it says you have to graph it.

The graphing can be done using the GDC, Excel, Graphmatica or Graph.

I like the last 3 better than the GDC.

If I understood it correctly, you're supposed to find values of k that makes the expression an integer, and it doesn't say anything about graphing there. The infinite surds of 1 and 2 should be graphed though, but that's in the beginning.

I used as many significant figures as my GDC would allow and I think that's enough, even though some more probably wouldn't be a bad thing, especially since the infinite surd of 2 doesn't approach what it looks like on the decimal values...

##### Share on other sites
If I understood it correctly, you're supposed to find values of k that makes the expression an integer, and it doesn't say anything about graphing there. The infinite surds of 1 and 2 should be graphed though, but that's in the beginning.

I used as many significant figures as my GDC would allow and I think that's enough, even though some more probably wouldn't be a bad thing, especially since the infinite surd of 2 doesn't approach what it looks like on the decimal values...

You're talking about Part C ?

I think our school tweaked the portfolio a bit though.

I was talking about forming a general case... like a general equation that would give you the number the surd approches for any value of k...

##### Share on other sites

Ours wasn't divided into parts... I didn't graph anything when it came to the general case. This is getting a bit confusing, I don't really think we understand which parts we're talking about (at least I don't)

##### Share on other sites

I was talking about forming a general case... like a general equation that would give you the number the surd approches for any value of k...

I have that too but I don't really understand what they mean by a "general statement" can someone help me out?

##### Share on other sites

We also got this one in our SL class a few months back. I had a lot of fun doing it.

Tip to everyone; use spreadsheets to calculate the values rather than a GDC, that way you can see a lot more sig figs. Also, by using spreadsheets you can just enter in a general formula and it will give you as many values you want.

• 1

##### Share on other sites

We also got this one in our SL class a few months back. I had a lot of fun doing it.

Tip to everyone; use spreadsheets to calculate the values rather than a GDC, that way you can see a lot more sig figs. Also, by using spreadsheets you can just enter in a general formula and it will give you as many values you want.

but what do you mean by a general formula? :/

• 1

##### Share on other sites

We also got this one in our SL class a few months back. I had a lot of fun doing it.

Tip to everyone; use spreadsheets to calculate the values rather than a GDC, that way you can see a lot more sig figs. Also, by using spreadsheets you can just enter in a general formula and it will give you as many values you want.

but what do you mean by a general formula? :/

If you use Excel, then you can write in a formula like; =(A2*C2)+B2, and if you copy it to other cells, it will automatically change according to the cell.

• 1

##### Share on other sites

We also got this one in our SL class a few months back. I had a lot of fun doing it.

How can anyone enjoy doing maths IAs?

• 2

## Create an account

Register a new account