







Matrice 
20060201 

Kader pose la question : mon probleme est le suivant soit deux matrices carrees A et B d'ordre n qui sont anticommutatives AB= BA , demontrer que au moins une des deux matrices n'est pas inversible si n est impair.
je n'arrive pas a utiliser le fait que n soit impair, trouver le rapport entre n impair et inverse des matrices, je pars sur la base de DETAB=DETA*DETB Claude Tardif lui répond. 





probleme de matrice 
20060201 

Un eleve pose la question : mon probleme est le suivant soit deux matrices carrees A et B d'ordre n qui sont anticommutatives AB= BA , demontrer que au moins une des deux matrices n'est pas inversible si n est impair. Claude Tardif lui répond. 





Matrices 
20131110 

Ricky pose la question : Why must we have brackets around matrices. Why don't we just neatly write an array of entries crosswise and up and down to indicate a particular matrix? Chris Fisher lui répond. 





Geocaching 
20101015 

Clint pose la question : I am stuck on a puzzle for Geocaching which is a GPS game.
I know it is a number matrix but don't know how to start.
[1 7 16 3 9; 1 3 18 20 33] x [1 8 9 3 5; 0 1 0 4 2; 0 0 1 2 1; 0 0 0 1 1; 0 0 0 0 1] = ? Stephen La Rocque lui répond. 





The column space of a matrix 
20090212 

John pose la question : Question from John, a student:
A=
1 1 0 0
1 1 0 0
0 0 1 0
0 0 1 1
B=
1 5 6
1 5 6
0 7 2
0 0 9
Is the space spanned by the columns of A the same as the space spanned by the columns of B? Harley Weston lui répond. 





A linear system 
20080823 

dipesh pose la question : consider the system of equations
x6y+2z=5
2x9yz=14
4x+12y3z=19 by reducing the augm matrix to row echelon form, find
the solution to the equation.
leaving the first two equations the third is changed to 3x+6y+14z=31
show the equations have infinitely many solutions and give a general
formula for them Penny Nom lui répond. 





Determinants 
20080502 

Henry pose la question : I have a question about solving 3x3 matrices.
The traditional way, or at least the way I've been taught, is that if one has a 3x3 matrix such as:
[ a b c ]
[ d e f ]
[ g h i ]
one solves it according to this formula:
[ei  hf)  (bi  hc) + (bf  ec) = determinant.
According to a book I'm now studying to prepare for the California CSET exam, there is another, easier, way to solve it:
[ a b c ] [ a b ]
[ d e f ] [ d e ]
[ g h i ] [ g h ]
In other words, one repeats the first two rows of the matrix and adds them to the right.
At this point, the determinant is calculated thus:
(aei) +(bfg) + (cdh)  (gec)  (hfa)  (idb).
Is this, in fact, correct? Harley Weston lui répond. 





Matrix multiplication 
20080408 

manashi pose la question : i. why matrix division is not possible?
ii.when we add or subtract two matrix , getting the result by addind or subtracting correspondind elements....but in case of multiplication it is not but why? Harley Weston lui répond. 





Who is taller: John or Mary? 
20050914 

Ulises pose la question : All the students in a school are arranged in a rectangular array. After that, the tallest student in each row was chosen, and then among these John Smith happened to be the shortest.Then, in each column, the shortest student was chosen, and Mary Brown was the tallest of these. Who is taller: John or Mary? Penny Nom and Claude Tardif lui répond. 





A matrix problem 
20050404 

Alan pose la question :
Let A = 

1  1  0 

2  1  2 
a  b  c 
where a, b, c are constant real numbers. For what values of a, b, c is A invertible? [Hint: Your answer should be an equation in a, b, c which satisfied if and only if A is invertible.]
Judi McDonald lui répond. 





Two matrix problems 
20050330 

Sue pose la question : Question 1
Suppose all matrices in the equation below are square and invertible. Solve for x .
BA1XB1 + 2BA + In = 0 (the symbol "0" here denotes the matrix of all 0's in it)
Also, A1 or B1 is indicating inverse and "In" = for example, A1 times A
I hope you understand the above. I have to show all the steps.
Question 2
Suppose we consider the set of all 2x2 matrices along with the operations of matrix addition and multiplication. Do they form a field? Why or why not?
I think the answer is no because under multiplication it is not commutative and not all square matrices are invertible. I not positive so I'd like some help. Penny Nom lui répond. 





A matrix construction problem 
20050314 

Marcelo pose la question : I want to know if is it possible to solve this problem:
I have an empty NxM matrix and I know totals (sum) by rows and totals by column.
Is there any algorithm to fill the matrix so that the summary of columns and rows gives the original values I have? Harley Weston lui répond. 





Arrays 
20040219 

A parent pose la question : please demonstrate mathematical arrays fro a 3rd grader Penny Nom lui répond. 





Matrices 
20031205 

Julie pose la question : I am doing a project and need to find some mathematiciens who had an influence in matrices. I can't seem to find any when I search online. Could you please help me with this? Judi McDonald lui répond. 





A determinant 
20030213 

A student pose la question :
I have to find the determinant of the following matrix 2  3  1  2  4  3  0  2  5  1  4  2  1  3  5  2  3  4  1  2  6  0  3  2  4  Penny Nom lui répond. 





Matrix 
20011121 

Hoda pose la question : I have a question about matrix multiplication; well, actually, matrix division. I am assuming that matrices are divided the same as they are multiplied; that is, row by column. But what happens if you have to divide by zero? How does this affect the resulting matrix? Patrick Maidorn and Penny Nom lui répond. 





Conformable matrices 
20010805 

Wayne pose la question : Can someone explain the concept of conformable matrices in a way that is easy to understand ? One definition says to multiply matrices rows and columns must conform, ie, 5 x 3 matrix times a 3 x 5 matrix. In the next example, however a 8 x 1 matrix and a 8 x 3 matrix are said to be conformable! Steve Kirkland lui répond. 





Matrix reconstruction 
20010719 

Guy pose la question : Is there a way to get the sums of rows, columns and diagonals of an n x n matrix to reconstruct the original matrix? Walter Whiteley and Patrick Maidorn lui répond. 





Matrices 
20010326 

Peg pose la question : What are some applications of matrices, basic trigonometry, and linear systems in the real world? I'm writing and Algebra report about where these topics are used outside of the classroom. Judi McDonald and Walter Whiteley lui répond. 





Solving Equations 
20010223 

Stephanie pose la question : Do you know who came up with solving equations? Do you have any websites that can give me good information on solving equations? Do you know any history on solving equations? Do you know what solving equations is used for? And finally............Sorry about all of the questions :) Has the form of solving equations changed from the time it came out to now? Juci McDonald lui répond. 





Where will we use this in the real world? 
20001011 

Jane Ann Musgrove pose la question : As a teacher of mathematics, I am always asked "Where will we use this in the real world?". I am seeking ideas/sites via the internet where students can find answers to this type of question. Can you help me? To be more specific, right now I am interested in finding careers where the employees would use the concepts of "Radicals", "Matrices", and "Logarithms". This information will be used by students to make presentations to the class on their findings from internet searches. Harley Weston lui répond. 





A matrix equation 
20000514 

A student pose la question : Right now, we are dealing with matrices and we are supposed to solve the following problem on our graphingcalculators: 2a+3b4c+d=20 a2b+3c5d=14 3a+4b2c+3d=19 5ab+6c+4d=5 Penny Nom lui répond. 





Matrices Information 
20000502 

William Avery pose la question : I am an OAC student at Governor Simcoe Secondary School in St. Catharines Ontario. Today at school we were handed an independent study project by our Finite teacher. This assignment is based on Matrices, it involves performing some simple matrix calculations, but also involves a written section. This written section asks for the following: . . . Marley Weston lui répond. 





Taxis in Chicago 
20000327 

A high school studenthigh school student pose la question : Suppose that taxis pick up and deliver passengers in Chicago, which is divided into three zones. Records kept by the drivers show that of the passengers picked up in Zone 1, 50% are taken to a destination in Zone 1, 40% to Zone 2, and 10% to Zone 3. OF the passengers picked up in Zone 2, 40% go to Zone 1, 30% to Zone 2, and 30% to Zone 3. Of the passengers picked up in Zone 3, 20% go to Zone 1, 60% to Zone 2 and 20% to Zone 3. Suppose that at the beginning of the day, 600 of the taxis are in Zone 1, 100 in Zone 2, and 300 in Zone 3. What is the distribution of taxis in the various zones after all have had two riders? Harley Weston lui répond. 





Matricies 
19981126 

Stephanie Webster pose la question : If a matrix for a rectangle looks this way: AACC BDDB What does the matrix for a square look like? Penny Nom lui répond. 





Mathematical Arrays 
19980501 

Gene Lanctot pose la question : Could someone please explain what a mathematical or arithmetical array is? The array in question is used in grade three math in Ontario. I would also like to know what its purpose is. Harley Weston lui répond. 





Matrices 
19980310 

Ksya pose la question :
 A and B are matrices. If A^n=B^n, can we say A=B or det(A)=det(B) or det(A)^n=det(B)^n ? Any conditions ???
 If B^(1) is the inverse of B, where B is a matrices. Can we say [(B^(1))^n][B^n]=I, where I is identity matrices? Any conditions???
Doug Farenick lui répond. 

