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**katecaroline****Member**- Registered: 2005-06-19
- Posts: 35

Hello, I'm Kate.. I just joined the forum. Woo! It was kind of fluke that I found it because I was studying for my Math exam tomorrow and needed some pointers. Wish me luck! >.< Ah I hate finals. Anyway a little bit about me I guess.. my name's Kate. I am 15, and I live in Canada . Yay. Anyway I must be off.. I want to explore this site a little more. Bye--

» I always knew that looking back on the tears would make me laugh,

but I never knew looking back on the laughs would make me cry. «

<3

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,604

Hi there Kate, and a BIG welcome to the forum.

How did that exam go?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**justlookingforthemoment****Moderator**- Registered: 2005-05-26
- Posts: 2,161

Like your avatar.

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**Zach****Member**- Registered: 2005-03-23
- Posts: 2,075

That avatar is hypnotic.

Boy let me tell you what:

I bet you didn't know it, but I'm a fiddle player too.

And if you'd care to take a dare, I'll make a bet with you.

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

Welcome Kate!

Hooray! I'm not the only girl anymore!

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**katecaroline****Member**- Registered: 2005-06-19
- Posts: 35

Haha hello everyone! The avatar is indeed hypnotic XD I made it myself haha. Oh the talent .

My exam was quite good thanks! Very long, but pretty easy. Only a graphing problem I think i totally messed up haha. Aw well it's only graphing. Anyway I had no idea I was pretty much the only other girl. lol that rocks! woo

» I always knew that looking back on the tears would make me laugh,

but I never knew looking back on the laughs would make me cry. «

<3

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,604

There are one or two people here who MAY be girls, but they aren't saying.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**katecaroline****Member**- Registered: 2005-06-19
- Posts: 35

Haha I'm deffinatly a girl I know that much But I'll just keep a suspicion about Roraborealis then hehe.

» I always knew that looking back on the tears would make me laugh,

but I never knew looking back on the laughs would make me cry. «

<3

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**katecaroline****Member**- Registered: 2005-06-19
- Posts: 35

"MathsIsFun " just a quick question, are you a mathmatician? I have no idea of your age.. but judging from your other posts I've read it seems as if you have the knowledge of university math. Haha if you're only a teenager or something then congratulations on your insane brain ;P

but I never knew looking back on the laughs would make me cry. «

<3

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,604

You are right, katecaroline, I did a few math units at University. Calculus, matrix algebra, stuff like that. But don't ask me anything TOO difficult, ok?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

katecaroline wrote:

But I'll just keep a suspicion about Roraborealis then hehe.

What? I am a girl, and I follow in the footstpes of George Washington.

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**justlookingforthemoment****Moderator**- Registered: 2005-05-26
- Posts: 2,161

Roraborealis wrote:

Hooray! I'm not the only girl anymore!

*clears throat* umm...

* what about me? *

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

Ummmm, I thought you *weren't*.

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**katecaroline****Member**- Registered: 2005-06-19
- Posts: 35

MathsIsFun wrote:

You are right, katecaroline, I did a few math units at University. Calculus, matrix algebra, stuff like that. But don't ask me anything TOO difficult, ok?

Lol don't worry I wont. My math knowledge does not inclute matrix algebra and such

..or it doesn't yet anyway muahaha.

but I never knew looking back on the laughs would make me cry. «

<3

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**Mr T****Member**- Registered: 2005-03-30
- Posts: 1,012

i don't know nuffin bout no matrix algebra. what is matrix algebra?

I come back stronger than a powered-up Pac-Man

I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large

Fatboy Slim is a Legend

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,604

A matrix is an array of numbers like:

[ 3, 5 ]

[ 0, 8 ]

You could add this to another matrix and get something like:

[ 3, 5 ] + [ 1, 2 ] = [ 4, 7 ]

[ 0, 8 ] [ 3, 1 ] [ 3, 9 ]

Yay! I did Matrix Addition!

Now onto Matrix Multiplication ... now, how would I do that? Should I just multiply the matching numbers? Or multiply everything by everything? Answers to this and more will be revealed when you study Matrices.

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

I'm going to uni when I'm older and 'm gong to study maths!

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**Mr T****Member**- Registered: 2005-03-30
- Posts: 1,012

that is well confusing!!! but i can kind of understand, when could it be used though

I come back stronger than a powered-up Pac-Man

I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large

Fatboy Slim is a Legend

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,604

Roraborealis wrote:

I'm going to uni when I'm older and 'm gong to study maths!

Good on you! I did my maths as part of an engineering degree - we already had to do a lot of maths, and then I took extra maths units as electives.

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

I plan to teach maths.

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,604

Oh, yes, I remember you saying you wanted to teach at Uni. Is that right? Or do you want to teach school kids?

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**Mr T****Member**- Registered: 2005-03-30
- Posts: 1,012

i am doing my work experience at an infant school and i looking foward to it...

I come back stronger than a powered-up Pac-Man

I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large

Fatboy Slim is a Legend

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

MathsIsFun wrote:

Oh, yes, I remember you saying you wanted to teach at Uni.

Such is my ambition.

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**katecaroline****Member**- Registered: 2005-06-19
- Posts: 35

Ah I know much of matricies But Matrix algebra.. I assume that's just marticies involving algebraic numbers and unknowns? eh EH?

but I never knew looking back on the laughs would make me cry. «

<3

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,604

Yes, quite right. There are special rules for Matrices.

(Hold on to your hat, now, and I will try to explain a little - this may help you guys later ...)

For example you can't divide by a Matrix, but you can (sometimes) "Invert" a Matrix and Multiplying by an Inverse is the same as dividing.

So, let us say you know Matrices A and B, but don't know Matrix X in the following:

AX = B

Then, how do you find out Matrix X?

If you can invert Matrix A to become **A^-1** (that is supposed to be an A with a neat little "-1" in the corner), then you can multiply both sides by **A^-1**:

**A^-1** * AX = **A^-1** * B

And **A^-1** * A cancel each other out (just like 1/7 times 7 would), so you get:

X = **A^-1** B

**How Is This Useful ?**

It can let Engineers, Scientists, Economists, etc play with large sets of equations. If you can figure out how to use matrices to express a problem, then you can get a program to crunch the sums for you.

Here is a really simple problem - we could solve it ourselves, but you could imagine that instead of 2 equations there were 200 to solve together:

3x + y = 7

x + 2y = 4

In Matrix form this would be:

[ 3 1 ] [x] = [7]

[ 1 2 ] [y] [4]

The Inverse of [ 3 1 ] is [ 2/5 -1/5 ] (Just believe me, OK? There is a standard pattern to follow to get there)

[ 1 2 ] [-1/5 3/5 ]

So the answer is:

[x] = [ 2/5 -1/5 ][7]

[y] [-1/5 3/5 ][4]

Multiplying matrices follows a standard pattern, too. In this case I will write it out longhand:

x = 2/5 * 7 + -1/5 * 4

y = -1/5 * 7 + 3/5 * 4

Calculating, the answer becomes:

x = 14/5 - 4/5 = 10/5 = 2

y = -7/5 + 12/5 = 5/5 = 1

As you can see, there is a fair amount of calculation involved, but that is what computers are for. So a program could handle a problem that had hundreds or thousands of equations for you.

So, YOU, the designer would work out the "Matrix Algebra" needed to solve your problem, then just tell the program "Invert A, multiply it by B ... " etc

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