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#301 Re: Help Me ! » About the prime factoring » 2007-03-17 16:40:25

I think as the number increases , prime become more rare , it'll be easier to do it.

#302 Help Me ! » About the prime factoring » 2007-03-17 16:16:03

Stanley_Marsh
Replies: 3

I 've though of sth , but don't know whether it's useful or not , but can speed up a little

For example ,  the number 679543

if

we just need to find p.


But the range is still to large , then assume 679543=qpm , then 

Assume that  679543=abcd , then


Try , 23,19,17,13,11, 7 5, 3, 2, ,find out that none of them can divide the number , then the number may be the product 3 primes or 2 primes .
   I don't know if this can help.

#305 Re: Help Me ! » Is there any shortcut? » 2007-03-15 15:38:16

Yah~true , that will bring a huge revolution ~hehe and turbulence

#306 Re: Help Me ! » partial derivatives problem » 2007-03-15 15:35:35

it's just my opinion , if you see w as a constant , then  the derivative will be

where w equal to 130

#307 Re: Help Me ! » partial derivatives problem » 2007-03-15 15:27:51

1) His weight remain constant , you can see w as a constant then find the derivative

#309 Re: Help Me ! » Need help in trigonometry » 2007-03-15 15:06:29

I havent really learned about limit, calculus and stuffs , never take them seriously, When I saw this one, I thought of

, too .
  mathsyperson's proof exccedes my knowledge lol , But I think I've got the idea.lol

#310 Re: Help Me ! » Is there any shortcut? » 2007-03-15 15:02:09

We can divide n by a the prime we find because we know that n is a product of distinct primes, and so once we find one, we can "take it out" of n.

but if a number is the product of two 22 digits primes , then ....

If I can find a method ~WOW~lol ~jk

#311 Re: Help Me ! » Need help in trigonometry » 2007-03-15 10:21:55

Don't let this one sink ,  It's a good question ,guys. I can't work it out tho

#312 Re: Help Me ! » pythagorean triplet » 2007-03-15 10:20:29

  let y =14  then mn=7 , let m=7 n=1
we have  x=48 z=50 ,y=14

#313 Re: Help Me ! » Is there any shortcut? » 2007-03-15 10:18:38

Lol~ that's programming method ,right?

#314 Re: Help Me ! » pythagorean triplet » 2007-03-15 06:32:44

The generator is carried out by observation  of X^2+Y^2=Z^2 , if you put them back into the original formula , you will find , two side of it are equal .

#315 Re: Help Me ! » Check my proof guys » 2007-03-15 06:30:23

but there's little beyond my knowledge ,

#316 Re: Help Me ! » Check my proof guys » 2007-03-15 06:27:31

Oh , I miss your proof , sorri~ Yep , that's it

#317 Re: Help Me ! » Check my proof guys » 2007-03-15 06:23:14

then I shall prove

I shall show 5 will always divide one of the following:
Hmmm,Shall I consider each set of ridues ?

#318 Re: Help Me ! » Strange Natural Number Pair » 2007-03-15 06:00:24

According to above , the two numbers of yours , (A,B)=1 , then there must be p,q such that Ap+Bq=gcd(A,B)=1

#319 Re: Help Me ! » Strange Natural Number Pair » 2007-03-15 05:52:36

Here is another version of proof from my textbook

Let H be the subset of Z consisting of all integer of the form


Then H is a subgroup of Z and
. By theorem ",Let H be a subgroup of the integers under addition, There exist a unique nonnegative integer d  such  that H is the set of all multiples of d , that is
", there exists a unique positvie integer d drag that H=dZ, that is , H consists of all multiples of d , In particular , every integer
is a multiple of d , and so d is a common divisor of A. Since
, there exist integers

#320 Help Me ! » Is there any shortcut? » 2007-03-15 05:35:59

Stanley_Marsh
Replies: 8

The unique factorization theorem says that every positive integer number greater than 1 can be written in only one way as a product of prime numbers.

   Is there a way I can find those prime faster? so I don't have to try all the primes less than that integer.

#322 Re: Help Me ! » 7 » 2007-03-15 05:30:29


, it has to be a square so  n= 11 ,actually this can be noticed when

#323 Re: Help Me ! » pythagorean triplet » 2007-03-15 05:18:55

As in my early post , the generator of the triplet

, m, n random integers.

#324 Re: Help Me ! » can someone help through this so can help my daughter on the weekend?? » 2007-03-14 18:06:02

What you mean is

right? if so , it's a parabola
, the coefficient of the 2 power p is negative , which indicates that the parabola is downward(I am not sure if you understand what I mean , I am not very good at explaining detail)
Then it has a maximum value whose x-coordinate is equal to
where a=-50 ,b=1500

#325 Re: Help Me ! » Check my proof guys » 2007-03-14 11:49:59

Oh ,yeah , If I just prove

for
there is always an odd k that makes it be divided by 5 , will that work?

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