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Cmdr. Cracken
01-30-2001, 06:51 PM
Keyan, or any other math geniuses, can you help me under stand functions and function notation? (Not in C++, ADV. ALGEBRA)

JR2000Z
01-30-2001, 07:02 PM
Im sure we can.

Admiral
01-30-2001, 07:09 PM
a function is anything that passes the the y axis only once.

for instance

f(x)=2x(sq)+x

if you give a number say 4 you get.

2(4)(sq)+4=36

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"Dulce bellum inexpertis."
(Sweet is war to those who have never experinced it.) Roman Proverb

Rogue Nine
01-30-2001, 07:09 PM
You could show them to us, dunno if I personally will be of any help...

Keyan Farlander
01-30-2001, 07:44 PM
Originally posted by Admiral:
a function is anything that passes the the y axis only once.


NO!!! That is not true at all! It is true that if it does pass the y axis more than once, it is not a function, but it needs much more to actually be a function.

A function is a mapping from one set of values to another. The key is that no element from the domain ("mappers") can map to more than one element of the range ("mappees"). Now, two or more elements of the domain can map to the same member of the range - that makes no difference. So if you think about it in terms of the graph, no two points can be on top of each other. The graph cannot cross ANY vertical line more than once.

Rogue Nine
01-30-2001, 07:48 PM
The great and amazing Keyan has spoken! Be stupefied!

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Love people. Use things. Not vice versa.
XWA's Resident Finance Manager

Keyan Farlander
01-30-2001, 08:38 PM
You know it, baby. I may be a loser in almost everything else, but I know my math.

Darth Sceltor
01-30-2001, 08:43 PM
My head hurts.

Psycho Tycho
01-30-2001, 10:05 PM
Yeccch, math. Forget about math. Yeccch, school.

Rogue Nine
01-30-2001, 10:11 PM
Just giving him the props he deserves.

Zoom Rabbit
01-30-2001, 10:51 PM
I function as a biological perambulation unit!

Admiral
01-30-2001, 11:03 PM
Your right Keyan. I haven't used functions for over a year so...must have forgotten some. we need to chat some math some time.

Cracken if you can post some problems I could help some more.


------------------
"Dulce bellum inexpertis."
(Sweet is war to those who have never experinced it.) Roman Proverb

Gold leader
01-31-2001, 10:55 AM
Originally posted by Admiral:
a function is anything that passes the the y axis only once.


Admiral, you should have known better. f(x) = 1/x is a function, but it never actually passes the y-axis.

Rogue Nine
01-31-2001, 11:15 AM
Not true. Try the function (x-4)^2/x-2.

Gold leader
01-31-2001, 11:35 AM
Try what. Differentiate?

Rogue Nine
01-31-2001, 03:10 PM
Graph it.

Keyan Farlander
01-31-2001, 05:29 PM
Why? It's pretty obvious what it will look like.

Rogue Nine
01-31-2001, 05:45 PM
Yeah, but no one else is a frickin' genius like you, Keyan.

Keyan Farlander
01-31-2001, 06:07 PM
Um, thanks http://www.xwingalliance.com/forums/smile.gif But I meant what is your point about graphing that? I'm not sure what you're getting at. Something about the discontinuity?

Rogue Nine
01-31-2001, 06:40 PM
Tis a line, isn't it?

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Love people. Use things. Not vice versa.
XWA's Resident Finance Manager

Admiral
01-31-2001, 07:06 PM
I am bad with graphs, I like using my calculator for those.

------------------
"Dulce bellum inexpertis."
(Sweet is war to those who have never experinced it.) Roman Proverb

Rogue Nine
01-31-2001, 07:21 PM
So try it! Plug it in!

Keyan Farlander
01-31-2001, 09:17 PM
A line? That function is not a line. Speak up, R9, what are you getting at?

Cmdr. Cracken
01-31-2001, 10:47 PM
so, how would i evaluate this.....?

g(x)=x^2-3x
when g(4)

would I just substitue x for for, since g(4)?

Cmdr. Cracken
01-31-2001, 10:50 PM
I think i know what R9 is getting at. a function is any line on a graph that passes the vert. Line test.

Vertical line test=You place a vertical line anywhere on the line. if the vertical line crosses the line more than ONCE, then the line is not a function.

R9's sentence (x-4)^2/x-2 will probably fail this test.

Keyan Farlander
01-31-2001, 11:07 PM
Yes, that is how you do it. And that thing passes the vertical line test with flying colors.

JR2000Z
01-31-2001, 11:09 PM
Hehehehehe...*cough* sorry. http://www.xwingalliance.com/forums/biggrin.gif

Gold leader
02-01-2001, 08:36 AM
Originally posted by Cmdr. Cracken:
so, how would i evaluate this.....?


g(x)=x^2-3x
g(4)=4^2-3*4=4

piece o' cake.

Zoom Rabbit
02-01-2001, 09:27 AM
I was told we didn't have to do math...!

Rogue Nine
02-01-2001, 10:22 AM
I'm too sleepy. Math stinks. 'Specially at 6:30 in the morn.

Zoom Rabbit
02-01-2001, 10:40 AM
Cool.

*(Plays videogames instead.)*

Rogue Nine
02-01-2001, 10:41 AM
You're a woozer...don't you have to go to school?

Jem
02-05-2001, 07:28 PM
Here is a twisting math resolution for you guys:

1+1=1 so 1+1=3 (we can also say that 1=2=3)

and this is why (the bold parts are the changes that occured):

(a+b)(a-b) = a - ab + ba - b
(a+b)(a-b) = a - b
_Now divide each side by (a-b), we have:
[(a+b)(a-b)]/(a-b) = (a - b)/ (a-b)
_We now have:
(a+b) = (a - b) / (a-b)
_Let us suggest that: a = b = 1
which gives us:
1+1 = (1-1) / (1-1)
_There is the same terme above and under the division so it is equal 1
so we have:
1+1 = 1
_add one at each side:
1+1+1 = 1+1
3 = 1 + 1

There you go!
(we can also conclude that 2 + 2 = 5 and etc. Also we can show that 1=2=3=4=5=etc)
Any comments?

Keyan Farlander
02-05-2001, 11:08 PM
Um, you can "prove" almost anything if you sneak a divide by zero in there. There are so many bogus proofs that use this that it can be called "a really old joke" in math circles. I actually seem to recall us having this discussion here a little while ago (although it might be somewhere else I was thinking about). I remember the first time I saw something like this. It WAS actually pretty freaky http://www.xwingalliance.com/forums/smile.gif

Nitro
02-06-2001, 01:31 AM
If it passed the vertical line more then once, that would make it a parabola, and therefore quadratic, and not a linear equation.

I hate quadratic equations... not cause they don't make sense, or they're hard... They're just the same thing over and over again... No challenge.

Nitro
02-06-2001, 01:36 AM
I'm doing Enriched Grade 11 Math, and Advanced Enriched Grade 12 Math in the same semester so I can do my Calculus and AP Math next year... but we haven't started any serious algebra yet, so I'm lost, but wanted to feel cool and in with the math geeks, so I posted some random fact that's true... Shows how great my life is... I'm reaching to the Math geeks for acceptance. http://www.xwingalliance.com/forums/biggrin.gif

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Hello, my name is Nitro, and I'm calling from BBM Bureau of Measurement, the radio ratings company...

Keyan Farlander
02-06-2001, 02:18 AM
Actually, there was a lot wrong with what you said http://www.xwingalliance.com/forums/smile.gif I think you meant horizontal line, first of all. Even so, it might be cubic or quartic or anything else of higher order. Not to worry, though - I accept you on behalf of all us math geeks http://www.xwingalliance.com/forums/biggrin.gif

Zoom Rabbit
02-06-2001, 12:09 PM
I represent the silent multitude of people who have no clear idea what you 'math geeks' have been talking about. http://www.xwingalliance.com/forums/wink.gif

I thought a 'vertical line test' was that embarrassing thing the cops make you do on the side of the road with everyone staring at you as they drive past...

Nitro
02-06-2001, 06:10 PM
Yeah... I knew that... http://www.xwingalliance.com/forums/biggrin.gif

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Hello, my name is Nitro, and I'm calling from BBM Bureau of Measurement, the radio ratings company...

Jem
02-06-2001, 07:29 PM
Originally posted by Keyan Farlander:
Um, you can "prove" almost anything if you sneak a divide by zero in there.

Yeah, I was waiting till someone mentioned it befor discussing it:
what if you do not suppose a zero but the term (1-1), therefor the rule can be applied, can it?


[This message has been edited by Jem (edited February 06, 2001).]

Cmdr. Cracken
02-06-2001, 10:53 PM
Jem, the term (1-1)=0

so basically, in your proof, your using an euphemism for 0.