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#126 Re: Help Me ! » 1/pi » 2006-12-30 03:21:38

DRASTIC ?
What means that?

#127 Re: Help Me ! » 285714! » 2006-12-29 08:16:14

Which Image?
If it's some kind of a graph of a function, then it should be Mathematica.
I've posted Maple images only 1 ro 2 times.

#130 Re: Help Me ! » 285714! » 2006-12-29 07:20:06

Nope.
It would be cool if it was.
I have it as a kind of present. It helps me much for some problems.
But there exist many free math programs - I've had a link somewhere - and some of them are even better than mathematica in some cases.

#131 Re: Help Me ! » four variables in three equations » 2006-12-29 06:57:22

It can be solved. But one of you variables(or maybe more) will be "floating" - that means, that it can be every element of some domain, and the other variables will depend of it.

#133 Re: Help Me ! » Equation solving wht next? » 2006-12-29 06:49:15


Solution:


Solution:
x=-2 : y elem R
x!=0,-2 : y=0


Solution:
x!=0,-2:

#134 Re: Help Me ! » Expressing # of different character combinations for a given character » 2006-12-29 06:42:03

er.neerajsrivastava wrote:

well for c program you can just use simple looping concept
like
sum=0;
for(i=n;i>=0;i--)
{
      sum=sum+pow(x,i);
}
isn't it simple?
is that helped you or you did it in another way?

Yep. But maths helps better, because we know:

.
This gives us simplier program:

double sum(double x, int n){
return (pow(x,n+1)-1)/(x-1)
}
(and more efficient, too)

#135 Re: Help Me ! » can yu make this question complete . justify! » 2006-12-29 06:36:28

er.neerajsrivastava wrote:

how can it be sure as s^2t itself is multiple of 7, i think atleast it should be s^4t.


So s^2t is a square:
s^2t=a*a (a=s^t)
AND...
7 is prime number.
Knowing that if a prime number divides a square of x, then it also divides x, we get:
7/s^t, so 7^2/s^2t

#136 Re: Help Me ! » expected number?? » 2006-12-29 00:27:05

No I haven't.
this doesn't depend of n. Using Pingenhole proncipe, my sum ends with b+1 balls, because it's thoughtless to go further.
I used something like this - I'm cuonting all the possible combinatins with k balls and computing the probability to make a combination of k balls, multyplying them, and summazing for all k form 2 balls to b+1 balls. This gives me the aritmetic mean of the wheighted elements in the list, so the expected number of balls. It's tricky to understand, that the probability to get a combination with mare balls is less than the probability to get a combination with less balls.
And, as you can see from the picture above, the formula works!

#137 Re: Help Me ! » 285714! » 2006-12-29 00:20:54

yep. What kind if relation are you looking for?

#138 Re: Help Me ! » can yu make this question complete . justify! » 2006-12-28 08:12:26

Nope. We're sure only for 7/s^t.
So 7^2/(s^t)^2 = s^2t, option 1

#139 Re: Help Me ! » solve and explain » 2006-12-28 08:07:39

I don't like this kind of question.
They make me feel the author could have posted them just to "test" us.

#140 Re: Help Me ! » expected number?? » 2006-12-28 07:54:44

Sorry for the ten posts.
Now - a little break

#141 Re: Help Me ! » expected number?? » 2006-12-28 07:17:02

Now, I cannot find closed form for this sum. Mathematica gave me:

,
where
is the base of the natural logaritm, and

is something called Exponention integral:

That I call cool! smile
GOOD QUESTION!
I'll post pictures soon.
[EDIT] Plot posted.
lxandempiricalresultslb1.gif

#142 Re: Help Me ! » expected number?? » 2006-12-28 07:08:11

I founded it at least!
I had to leave my original function, because the omega function became so complicated.
I used another approach, which is hard to explain, and now I have a formula, which agrees with the experimental results:
First, I defined a function, S:


And now, using this helpful function, define:

That's it!

#143 Re: Help Me ! » expected number?? » 2006-12-28 00:59:52

Back to work.
For better understanding of the Omega function, I'll try to find its values for small number of bins using brute-force

#144 Re: Help Me ! » 1/pi » 2006-12-27 22:18:03

I like it this way:

#145 Re: Help Me ! » Expressing # of different character combinations for a given character » 2006-12-27 22:11:31

This gives a polynomial of degree n, so your program should have complexity:

#146 Re: Help Me ! » proof √2 is irrational » 2006-12-27 22:04:50

It basically means that if √2 is a rational, than there exist integers a,b, (a,b)=1, such that a^2=2b^2, so 2/a^2, but 2 is prime, so 4/a^2. But then 2/b^2, so 2/b, and we ,have 2/a and 2/b ,so (a,b)>=2, which is contradiction.

#147 Re: Introductions » Hello everybody » 2006-12-27 13:55:16

Zhylliolom wrote:

More clever than Krassi? This may be dangerous.

Edit: Congratulations on post 1600, Krassi!

Thank you, zhyllioly! smile

#148 Re: This is Cool » Mathematical Intuition/Feeling ? » 2006-12-27 13:52:10

In my opinion the intuition and the knowledge are the most important.
If you don't have intuition, it will be hard to develop alone.
If you don't have knowledges, you'll waste your time end intuition on subjects, already discovered, instead of learning them.

#149 Re: Help Me ! » Counting number of combinations » 2006-12-27 12:33:39

Let

be the number of paths with length l, which end in A (, or B or C).
Then these are obvious:

(because of the symmetry)

And the recurrent relations:


Expanding the second:

So:

and:
for l>2
Simplifying:

Now, we should solve the above induction with initial values P_A(1) = 0 and P_A(2) = 2.
Solving the characteristic equation:


So:

Finding a and b form the initial conditions:


So:

And, at last:

and:

#150 Re: Help Me ! » solve & explain » 2006-12-27 12:15:27

Or, it just isn't a question:

balasvce wrote:

a power r<1
a power (r*s)>0

compare

option A : s and option B: 0
which is greater .

It doesn't end with question mark tongue

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