Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1301 Re: Help Me ! » Recurrent relation » 2006-01-01 11:48:08

I couldn't understand all of this but I can help you with the last equation:
c1≈2.5

#1303 Re: Help Me ! » D(x^x) » 2006-01-01 11:27:20

And for the integral - it can't be simplified.

#1305 Re: Help Me ! » Help with 3D rotation » 2006-01-01 11:16:23

Area = 5.66169988597863380413031960736...

#1307 Re: Help Me ! » Help with 3D rotation » 2006-01-01 10:49:38

And here's the proof thingy:
Let ff[x]=ƒ(x)
The wanted area won't change if we push it one up. We to this to reduce ff to positive function.
We want S+S1+S3.
(x,y) means point x,y.


But
(rectangular with 45 deg)

so S = INEGRAL - S2.

Now we'll find S1 and S3:

(rectangular with 45 deg)
(rectanguler with 45 deg)

Then

#1309 Re: Help Me ! » Help with 3D rotation » 2006-01-01 09:55:25

Ha, ha, ha!
I tougth a while and I got very simple geometric solution.
But you must wait a wnile to make a pictures.

#1310 Re: This is Cool » Function that dicsern the numbers? » 2006-01-01 05:28:04

But it's useless, because I don't know non-trivial terms for a function to be periodic.

#1311 Re: This is Cool » Function that dicsern the numbers? » 2006-01-01 05:21:49

I found something:
Number r is:
1.Rational, if the function

is periodic
2.Irrational, when HS_r[x] is not a periodic function.

#1312 Re: This is Cool » Fermat's last theorem » 2006-01-01 00:50:00

I think the following site is the best:
I'm following the proof that siva(thank you) gave me.
There you can download the full solution. Or you can do this by clicking:
here for zipped .pdf file
here for PostScript
and here for .dvi
(I've tested only the .pdf format)

#1313 Re: This is Cool » Fermat's last theorem » 2006-01-01 00:25:44

Here's a simple example:
we use the function f(x)=x^2.(picture 1)
f-¹(y) = {sqrt(y) (picture 2) OR -sqrt(y) (picture 3)}
Then the Riemann surface of the function f-¹(y) is the union of the plots(picture 4)

#1314 Re: This is Cool » Fermat's last theorem » 2006-01-01 00:12:52

3.(answer): I think I understood what is this.
But how to explain it?
A Riemann surface is a surface-like configuration that covers the complex plane with "sheets.". When we have a functin over the complex plaine C, which is not "single valued":
∃ z1,z2 ∈ C: ƒ(z1)=ƒ(z2)=y.
What will we get for the inverse function of ƒ(z)?

Here's "logical" answer:
ƒ-¹(z) =={ƒ1-¹(z) OR ƒ2-¹(z)}.
In the general case ƒ-¹(z) may be union of k "single valued" functions.
The riemann surface of ƒ-¹(z) is the union of the graphs of these functions.

We can use Euclidean plane, too.

#1316 Re: This is Cool » Fermat's last theorem » 2005-12-31 23:23:40

2 (answer). As i understood it is just  Euclidean plane. Is that right?

#1318 This is Cool » Function that dicsern the numbers? » 2005-12-31 23:15:39

krassi_holmz
Replies: 3

I need a function dic(x) that gives 1 when x is rational and 0 when it's irrational.
Please give me some advice.
I think there will exist such.

#1319 Re: This is Cool » Solving diophantine equations » 2005-12-31 23:12:53

OK. We have simple alogritm for ax+by. I know it as Euler's reduction algoritm.
The next general case:
ax^2+by=c

#1320 Re: This is Cool » Fermat's last theorem » 2005-12-31 23:10:36

I'm starting exploring internet...

#1322 Re: This is Cool » Fermat's last theorem » 2005-12-31 23:06:27

I have a great idea:
Do you want to understand it?
I'm offering to discute the proof from the begining to the end. We'll post what we don't understand.

Are you in?

#1324 Re: Help Me ! » Factor Theorem? » 2005-12-31 21:40:39

The coeficient for x^2:
(x-a1)(x-a2)(x-a3) =>-a3x^2-a2x^2-a1x^2
-(a1+a2+a3)x^2=+3x^2 =>
a1+a2+a3=-3

#1325 Re: Puzzles and Games » . » 2005-12-31 13:41:30

a[1]=const
a[2]=F[a[1]]
a[3]=F[a[1],a[2]]
a[4]=F[a[1],a[2],a[3]]

Board footer

Powered by FluxBB