
Please post any and all homework or other textbookstyle problems in one of the Homework & Coursework Questions...

Feb2313 09:25 AM
micromass

1 
31,636 
http://www.physicsforums.com/showthread.php?t=30021
Here's the thread, look at the last two pages, can anyone come...

Feb607 02:57 PM
Schrodinger's Dog

24 
3,677 
does anyone know how to prove the intersection of two open sets is open?

Aug2407 01:41 PM
matt grime

24 
8,541 
The definition of an open set S is that there exists, for any point x element of S, an open ball with center x, all of...

Oct1811 08:52 AM
nmvictor

24 
7,007 
what allow us to put x=a+b+c

...

Aug3108 06:05 PM
evagelos

24 
2,465 
I can't come to a comfortable conclusion which doesn't make positive, negative, real, imaginary, complex, irrational...

Sep2111 11:23 PM
Ntstanch

24 
4,609 
This is probably a noob question, background in probability theory isn't great but I was shown this problem in a...

Oct2711 01:19 AM
willem2

24 
4,937 
There are no actual paradoxes in mathematics (we hope). There are only things that appear to be paradoxes to fallible...

Oct912 09:32 PM
mXSCNT

24 
3,956 
This is the problem that a teacher (Kevi Spacey actually) presented the class on the movie 21:
You are on a TV show...

Dec1612 06:34 PM
broccoli7

24 
3,013 
Where do numbers come from? What is the logical basis for the existence of numbers?
Are numbers defined in...

Apr2913 08:53 AM
exponent137

24 
1,654 
Hi all. I've been thinking about this question a lot for the past few days and it seems to me that I'm committing a...

Jul713 08:24 PM
Stephen Tashi

24 
1,711 
This paper is still subject to being edited and I am an amatuer mathematician, so there may be some mistakes, typos,...

Jun2713 10:10 PM
krausebj0

24 
696 
my brother in law posed the following to me :
A contestant on a game show is presented 3 doors, one of which
has a...

Jan711 12:43 PM
Bacle

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22,924 
I need help with the following question on Resolution in FOL.
The custom officials searched everyone who entered...

Jan411 11:53 AM
Agaton

23 
2,307 
Greetings, comrades!
In a previous thread, a user articulated a common argument:
His analogy mapping...

Feb2812 11:18 PM
SW VandeCarr

23 
3,231 
Supposing X, Y and Z are three mutually independent continuous random variable, is multiplication X*Y and X*Z still...

Apr2212 09:39 PM
chiro

23 
2,953 
This is actually a problem from some biological data, but can be more generally described as follows:
I have a bag...

Jul112 11:20 AM
Sunnymilk

23 
1,538 
maybe this is too basic question but it is not so clear for me. when we refer to a random experiment, can a...

Apr1514 09:39 PM
chogg

23 
978 
I have some noisy data (xy coordinates) containing two distinct clusters of data. Each cluster is centred at an...

May2214 11:49 AM
jim mcnamara

23 
575 
Hi, I am having trouble with these proofs; I don't know if I am doing these right. I'd appreciate some help. Thank...

Jun105 08:25 PM
honestrosewater

22 
4,019 
Hi,
I just started a course about Statistics and I was wondering if I am doing the following question right.
Q:...

May2805 09:44 PM
KataKoniK

22 
20,608 
hi,
if A = {1, 2, 4, 6} and B = {0, 2, 3, 4, 5}
my understanding is that 1 is not a subset of A and 0 is not a...

Oct1011 04:32 AM
nickbyfleet

22 
49,978 
i have this question:
if: X=U X_i for every i in I, where X_i's are non empty and are disjoint, then X>=I....

Aug2108 09:27 PM
Kirk Hilliard

22 
2,212 
Suppose we consider flipping 100 quarters. The odds of all heads is 1 out of 2^100, which is about 10^30.
How can...

Jan2907 01:14 AM
ssd

22 
12,937 
Does anyone know how Cantor showed the existence of Transcendental numbers. How can he say that most numbers are...

May907 11:48 AM
EnumaElish

22 
3,166 
could you explain if we can define a main/basic concept of math and if terminology corresponds to concepts or is...

Oct2011 05:21 AM
pwsnafu

22 
3,138 
Hey everybody... I have a few quick questions concerning sets and functions for the experts... I've been trained in...

Aug2708 09:10 AM
evagelos

22 
11,508 
Hi, how would you show that 4^(k)+4 * 9^(k) \equiv 0 (mod 5)

Jan2109 02:14 AM
Mentallic

22 
1,921 
A circle is an infinite series of points equidistant from the center.
but can a circle be composed of an...

Jun209 04:57 AM
SW VandeCarr

22 
2,572 
Conditional Probability...
My handout says this...
P(m) = .4
P(w) = .5
P(mw) = .7
Find:
P(MnW) = ?

Sep2109 01:06 PM
SW VandeCarr

22 
2,278 
I know this can't be done but I don't know why. It's been established that the Axiom of Choice is required to prove...

Apr610 05:05 PM
SW VandeCarr

22 
3,227 
ok, so heres the problem:
given a 3 x 3 x 3 cubic system of vertices, a starting vertex, and an end vertex, how...

Jan312 07:05 PM
Edgardo

22 
4,987 
Here is a simple problem but with a lot of hidden difficulty:
We have a weather station somewhere in the country,...

Feb2411 09:58 AM
maswerte

22 
2,598 
A huge common misconception about brain function is that function can be localized to "very" specific locations....

Feb712 10:29 PM
PhysiPhile

22 
2,905 
You have k urns and M (M>k) balls.
Each ball is placed in a random urn (w/ uniform distrubution).
What is the...

Mar612 12:25 PM
SW VandeCarr

22 
2,494 
Hi,
When using data in calculations, errors can be introduced by the calculations themselves;
A common example...

Jul3012 10:12 PM
Stephen Tashi

22 
2,705 
I am confused about the counting of degrees of freedom. Yes, I know that it is the number of vectors which are free to...

Mar2813 02:08 AM
ssd

22 
1,945 
I’m working on ways to try and assess if data selection methods are capable of isolating accurate results (from a...

Apr1114 02:26 AM
geo101

22 
931 
OK, I have a question I have no idea how to answer (and all my awful undergrad stats books are useless on the matter)....

Sep310 05:06 PM
statdad

21 
104,196 
Hi!
I am having trouble constructing the sentences in this proof.
Its very simple, proof that A \cup \left( B...

Dec3009 07:37 PM
statdad

21 
4,229 
this is not a homework question, it was a interview question
Question:
suppose we keep flipping an unbiased...

Jul1010 08:54 PM
SW VandeCarr

21 
4,225 