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

Feb2313 09:24 AM
micromass

1 
30,537 
I'm looking at the exercises of Hungerfod's Algebra. Some looks easy but it seems the proofs are not so obvious....

Nov1109 12:27 AM
Spartan Math

4 
7,053 
write all possible equivalent conditions to "A is invertible," where A is an nxn matrix.

Nov707 07:55 PM
morphism

7 
7,031 
Hi everybody,
I'm new to absract algebra and I really can not understand different between direct sum and direct...

Mar1410 11:58 AM
Landau

9 
7,025 
Quick question: is the nullspace the orthogonal complement of the column space or the the row space?
Thanks, sorry...

Nov2204 05:21 AM
Galileo

2 
7,024 
If you have two groups, G_1 and G_2 and A is a common subgroup, then you can form the free product of G_1 and G_2...

Oct2506 10:30 PM
mathwonk

20 
7,014 
Cantor's diagonal slash has been used to argue that the infinity of reals is uncountable, whereas the infinity of...

Mar705 05:23 AM
Hurkyl

44 
7,009 
I'm working on some basic number theory. I came across an idea and I'm having trouble finding a general solution.
A...

Jun2807 11:08 AM
ramsey2879

3 
6,988 
I've been told that any number raised to the zeroeth power is equal to 1. What about zero raised to the zeroeth...

May2905 09:06 AM
matt grime

83 
6,980 
Hi everyone,
I'm in Grade 11 this year (in Australia), currently studying from Apostol's first volume "Calculus". I...

Jan1909 09:22 PM
wsalem

18 
6,968 
Just a conjecture...
If any realizable real is built from the integers, then the single smallest positive real is:...

Jun2104 01:22 AM
Jack Martinelli

16 
6,938 
I mean, according to my knowledge, Bertrand's postulate has already been proved, I've already read and understood one,...

Apr3010 04:11 AM
astroultraman

20 
6,938 
I have to prove that if ab is divisible by the prime p, and a is not divisible by p, then b is divisible by p.
In...

Aug604 08:10 AM
HallsofIvy

9 
6,922 
My lack of any shred of idea about the concept of the determinant is really beginning to bug me. Especially now that I...

Sep2010 12:09 PM
mathwonk

23 
6,921 
hmm.........

Sep3011 05:47 PM
lostcauses10x

19 
6,921 
A*A^T
Will result in a symmetric matrix. Does this mean that A*A^T will be positive semidefinite?
Does A have...

Nov2008 12:16 AM
D H

1 
6,879 
Prove that if A is an invertible matrix and AB = BC then B = C. I thought the way to approach it was to use A^1 on...

Oct1509 06:56 AM
HallsofIvy

1 
6,862 
Hi all,
i would like to tell me, how to find the modular multiplicative inverse (MMI), of a mod n...
Untill...

Dec310 04:38 AM
scouter

7 
6,860 
I am not sure I fully understand the extension of the Unique Factorization Theorem (UFT) to Gaussian Integers (GI), by...

Jul3008 02:54 PM
CRGreathouse

5 
6,837 
Some physics major told me:
"Linear Algebra is much more important then calculus"
Can anyone give weight to these...

Apr2509 04:05 AM
HallsofIvy

5 
6,830 
The question:
If G is the additive group Q/Z, what are the elements of the subgroup G(2)? Of G(P) for any positive...

Sep1208 01:50 AM
morphism

1 
6,829 
Given a commutative ring R with a unit, how do you prove that the product of two ideals, I1 and I2, is also an ideal?...

Aug1808 10:28 AM
udita

9 
6,827 
What do you guys think of this? I haven't been able to find any sort of verification from reputable sites.
"Edgar...

Oct606 12:08 PM
arildno

20 
6,826 
If G is an abelian group, a in G has order m, b in G has order n, and gcd(m,n)=1, show that ab has order mn.
I am...

Jan3004 08:44 PM
Jupiter

5 
6,805 
For any 10 digit natural number N in which
the first digit corresponds to the total no of 1's.
the 2nd digit...

Jun2909 02:12 AM
CompuChip

9 
6,804 
\ Let T: V \rightarrow W be a linear transformation, let b \in W be a fixed vector, and let x_0 \in V be a fixed...

Jun105 09:59 PM
mathwonk

4 
6,783 
What three digit prime number has all prime digits and forms primes with its first two and last two digits?

Dec1708 11:18 PM
robert Ihnot

14 
6,778 
How would I calculate the determinant of a square matrix using LU Decomposition. Please be plain, I am not good with...

Aug2009 10:11 PM
jeff1evesque

1 
6,762 
A little while ago I noticed a pattern in the sums of the digits of perfect squares that seems to suggest that:
For...

Apr1204 08:55 PM
honestrosewater

25 
6,758 
I'm trying to find the basis for a particular matrix and I get a 3 eigenvalues with two of them being identical to...

Nov904 11:11 AM
matt grime

1 
6,758 
There are two references frames, A and B.
Let A's reference frame be denoted by the columns of the identity matrix,...

Dec810 08:33 PM
p1ayaone1

5 
6,754 
I am trying to prove that for an integer n, if even, then n(n^2 + 20) is divisible by 48.
I have done all the...

May3105 01:49 AM
TenaliRaman

33 
6,749 
Does anybody know of any jobs that deal explicitly with Matrices and/or Linear Algebra? I have to do a paper and I...

Oct1907 12:43 PM
chapani

2 
6,745 
I read on http://www.cuttheknot.org/blue/Euler.shtml that the derivation of the Euler's formula for \varphi(m)...

Jan1708 05:16 AM
Eus

4 
6,745 
Greetings, I just stumbled upon this site and thought someone might be able to help me. How many elements of order 5...

Oct604 11:22 AM
Motifs

2 
6,742 
Hi all,
I have a problem with the question below:
Suppose that
2x_1 + x_2 + 3x_3 = 1
4x_1 + 6x_2 + 8x_3 = 5...

Mar3006 08:43 PM
wu_weidong

0 
6,739 
So I've shown that A and A^T have the same char. polynomials => same eigenvalues, using the fact that detA = detA^T. ...

Feb1508 04:19 PM
ObsessiveMathsFreak

2 
6,739 
I am curious as to why a subset of a vector space V must have the vector space V's zero vector be the subsets' zero...

Feb808 03:25 AM
mrandersdk

5 
6,738 
I am trying to find a way to generate solutions to 5b^2*c^2 = 4a^2(b^2+c^2)
Can anyone offer some insight?
I...

Dec1312 06:26 AM
ramsey2879

55 
6,709 
i was not sure where to put this topic since I don't know which subject of math grassmann math constitutes. Is there...

Aug2107 07:50 PM
Chris Hillman

1 
6,708 
Hi all,
I am trying to generalize a geometric concept found on page 7 from Steven Weinberg's "Gravitation and...

Nov1810 11:49 PM
chingkui

4 
6,708 