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

Feb2313 09:24 AM
micromass

1 
36,194 
How do I find out if a number is a perfect square modulo a? For example, is 4 (mod 10) a perfect square?

Jan205 07:21 PM
daster

9 
10,830 
I was doing a math project, and I was wondering if anyone knew how to solve a 4x4 determinant.

Oct2404 01:11 PM
HallsofIvy

4 
10,810 
Proof:
1. why you need at least m vectors to span a space of dimension m.
2. If m vectors span an mdimensional...

Mar2008 10:42 AM
HallsofIvy

8 
10,809 
I'm having a bit of a struggle with my assignment.
I'm supposed to find what is x in AxB = (B1A1)1 .
I'm...

Nov304 07:05 AM
HallsofIvy

2 
10,780 
I have been thinking about this for a week and I simply can't get anywhere.
consider a 4x4 diagonal matrix such...

Dec1607 09:48 PM
Defennder

1 
10,776 
Amateur question ahead, be warned.
I really dislike proofs that something cannot be done. My first gripe is that...

Apr1510 10:35 PM
CRGreathouse

18 
10,772 
I have the second printing of the first edition of Herstein's 'Topics in Algebra', published 1964.
On page 58 near...

Aug3008 01:05 PM
peter_n

6 
10,697 
Hey,
A while ago i hear about finding the division number theory . And i am wondering if there is a theory...

Oct2804 11:18 AM
Gokul43201

3 
10,692 
How is measure theory associated with number theory, if at all.
If they are connected, can anyone give a link?

Nov2107 04:02 PM
morphism

18 
10,671 
Do you ever think up theorums and think: "that's inetersting, I wonder if anyone's ever thought of that before?"
In...

Nov2305 12:34 AM
mathwonk

5 
10,654 
How would i start to solve this problem?
x^2 + 1 == 0 (mod 5^3).
Find all solutions.
How do i know how many...

Dec2004 10:15 PM
Hurkyl

2 
10,609 
I'm trying to learn linear algebra by myself from a book called "Introduction to linear algebra" by A.D. Martin and...

Dec3103 11:29 AM
Muzza

4 
10,544 
How do i find the eigenvalues and eigenvectors for the linear operator T defined as
T(w,z) = (z,w)??

Mar508 09:37 PM
mathwonk

6 
10,499 
What is the last digit of 2222^{50}~+~7777^{16}?
I know how to do these kinds of questions, but this time around I...

Sep909 07:42 AM
Borek

11 
10,495 
I'm just beginning my study of rings, and I'm wondering if there are some standard ways to show that two rings are not...

Apr2309 01:16 AM
matt grime

11 
10,457 
In the "origin of zero" thread, I saw the following remark:
I had heard a different story, in a pythagorean mood:...

Apr1605 01:34 PM
neurocomp2003

6 
10,432 
Hey,
I need help with thris proof.. :)
Say A is a skewsymmetric matrix. Is B=A^2 skewsymmetric, symmetric or...

Oct2306 12:37 AM
robphy

1 
10,414 
I find it rather tedious to calculate the eigenvalues of a 3x3 matrix. For example
The \emph{characteristic...

Apr1709 03:12 AM
matt grime

2 
10,410 
Hi, I'm a grad student in pure math and I'm trying to relearn my linear algebra from scratch because I never learned...

Nov1709 06:25 AM
Ruslan_Sharipov

7 
10,372 
There are 2 issues I want to talk about in this post.
(1) General algorithm for gaussjordan elimination computation...

Apr409 08:06 PM
junglebeast

0 
10,368 
Hi all! I was working on some homework for the linear algebra section of my "Math Methods for Physicists" class and...

Oct1409 03:00 AM
Matthollyw00d

2 
10,351 
I assume everyone who saw this thread first rolled their eyes. Sorry for that. My question is an innocent one, as I...

Jan2511 10:58 AM
Max™

39 
10,343 
If I have a set of numbers from 1 to N, I want to know how to count sets such that the highest number in the set is...

May2612 09:17 AM
ClifDavis

102 
10,327 
right now, my concept for their difference is that linear transformations are 1 to 1, where as nonlinear...

Nov509 04:04 AM
HallsofIvy

2 
10,306 
Wikipedia details the technique for converting from toroidal coords to cartesian. How do you convert the other way?
...

Feb2608 04:47 AM
pkleinod

22 
10,299 
I don't really understand why it hasn't been numerically added into modern math. I mean, we make all kinds of...

Mar1709 05:27 AM
HallsofIvy

66 
10,294 
I'm reading the Wikipedia article, trying to understand the definition of the tensor product V\otimes W of two vector...

Jun1808 11:43 AM
Fredrik

33 
10,282 
hi, i don't really understand whats the difference between vector product and dot product in matrix form.
for...

Apr2710 11:42 AM
quietrain

6 
10,273 
Hi.
Do you know of any package to draw Coxeter graphs and Dynkin diagrams in LaTeX directly?
Currently I'm...

Dec1907 05:00 PM
robphy

2 
10,227 
We have two nxn matrices with nonnegative elements, A and B.
We know the eigenvalues and eigenvectors of A and B....

Nov710 04:55 PM
Leo321

2 
10,215 
How do i get the point of intersection of a line and a circle.. I got lots of information on this topic, but my...

Aug709 07:26 AM
fatra2

3 
10,202 
How do I take the cross product of Two 3x3 Matrices.
For example what is cross product of:
x

Dec409 09:09 AM
dellatorre

5 
10,193 
how to plot the irrational number pi on a number line. i know the procedure for square roots of differant nonperfecr...

Nov1805 04:07 AM
Aditya89

7 
10,179 
While reading text, I had a question which I can not resolve by myself. Please Help me!
it reads, The empty set( a...

Sep2905 01:35 PM
Adriadne

33 
10,169 
Any explanation would be great. Also, are there any examples of finite Integral domains that aren't fields?

Feb411 09:03 PM
Spartan Math

7 
10,166 
Hi, has anyone else seen this news item http://www.physorg.com/news/201101maththeoriesrevealnature.html on how to...

Mar1711 05:26 PM
Raphie

12 
10,163 
Hi.
I have a question.
I know the rule of the hightest power of 2 dividing n!, the highest power means if 2^{k}n!,...

Oct2107 01:40 AM
whodsow

4 
10,104 
Hi all. I'm having a really tough time figuring out how to solve this problem:
Suppose that {v1, v2, v3} are...

Apr2311 08:00 PM
CatAteMyHW

6 
10,094 
Hello,
what's the difference between Hermitian and selfadjoint operators? Our professor in Group Theory made a...

Dec1608 01:19 PM
Adam....

10 
10,081 
Can you help me with this problem:
if a^2 divides b^2, show that a divides b.
This was a homework question that I...

Oct2409 05:42 AM
Bingk

23 
10,073 