  Math Central - mathcentral.uregina.ca  Quandaries & Queries    Q & Q    Topic: row sums   start over

3 items are filed under this topic.    Page1/1            Odds and evens in an n by n+1 table 2010-01-21 From Shankar:The boxes of an n * (n+1) table ( n rows and n+1 columns) are filled with integers. Prove that one can cross out several columns ( not all of them !) so that after this operation all the sums of the numbers in each row will be even.Answered by Robert Dawson.     Two matrix problems 2005-03-30 From Sue:Question 1 Suppose all matrices in the equation below are square and invertible. Solve for x . BA-1XB-1 + 2BA + In = 0 (the symbol "0" here denotes the matrix of all 0's in it) Also, A-1 or B-1 is indicating inverse and "In" = for example, A-1 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.Answered by Penny Nom.     A matrix construction problem 2005-03-14 From Marcelo: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?Answered by Harley Weston.      Page1/1    Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.    about math central :: site map :: links :: notre site français