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Average price 2017-09-15
From Annette:
If I sold a widget at $15.50 17.5% of the time and $16.50 88.5% of the time what is the algebraic expression for that. How do I arrive at an average price
Answered by Penny Nom.
What is the regular price? 2017-05-11
From Saira:
If the sale price is 55.50$ and the discount is 12% what is the regular price
Answered by Penny Nom.
Selling price and markup 2017-04-24
From Julie:
What would the cost of an item be, if the sell price was $50 and the markup 48%
Answered by Penny Nom.
How do I establish the original List Price? 2017-01-15
From Bob:
(1) I have a net price item at $4,664.66 but do not have the discount percentage. I have been told I received 40%? How do I establish the original List Price and to confirm what discount I received?
Answered by Penny Nom.
Selina saved $6 on a 20% off sale 2016-10-14
From Myra:
I don't know how to help my child answer this question - Selina bought a shirt on sale that was 20% less than the original price. The original price was $6 more than the sale price. What was the original price?
Answered by Penny Nom.
A 15% discount 2016-08-09
From eunice:
brian brought a printer sale at the store. the discount was 15%, and brian saved 550. what was the printer original price?
Answered by Penny Nom.
A 70% off sale 2016-05-11
From virginia:
If the sale price is $129.99 @ 70% off - what was the original price?
Answered by Penny Nom.
The original price before a discount and taxes 2015-12-09
From Michelle:
Good day,

I would like to know if there is a particular equation to validate the following information:

I had to find the original cost of an item sold for 759.36$ before a 25% discount and 13% taxes. I know we must use separate question to obtain the answer but I am unsure how to write the equation to validate my answer.

Answered by Penny Nom.
Two price reductions and a coupon 2015-09-16
From Suszanne:
Mary purchased an item for 45% off the original price, plus an additional 20% off the sale price.She also had a $5 off coupon, which the salesclerk applied after these two discounts. Mary's final purchase price for the item was $50. She paid no sales tax, what was the original price of the item?
Answered by Penny Nom.
What is our cost? 2015-01-27
From Johanna:
I have a pieces of 3/4" sch40 (round tube) 240" long at $70. What is our cost. We also add 35% to our cost for selling price. How do I figure this out?
Answered by Penny Nom.
Selling items at a reduced price 2015-01-09
From Kent:
I have an item I sell for $19.95 and make a profit of $10.97 for each sale. If I reduce the price to $14.97, my profit is $5.99 each sale. Is there a formula to determine how many more I would need to sell at $5.99 per sale to make the same net cash (profit) as selling at $10.97 per sale?
Answered by Penny Nom.
A price increase and a consumption decrease 2014-08-16
From sujan:
If the price of petrol increases by 25% and Rajesh intends to spend only 15% more on petrol then by how much % should he reduce the quantity of petrol he buys?
Answered by Penny Nom.
What was the selling price? 2014-04-25
From Con:
Apple built 40 32GB wifi iPads, gave away two in a contest, and sold the rest at two times the manufacturing price. If the company's total profit was $10,782, what is the selling price of one of these iPads?
Answered by Penny Nom.
Determine the selling price 2014-03-08
From augustine:
knowing an auctioneer charges a 7% fee and I know I want $74,400 what is the formula to determine selling price.
Answered by Penny Nom.
Finding the retail price 2014-02-22
From Judy:
An item is currently on sale at 37% off the retail price. The item now sells for $350.

My Question:

What is the retail price and what is the formula or steps to figuring that out?

Answered by Penny Nom.
A sale price for a TV 2013-11-28
From tom:
a TV can be purchased for $278 normally is $328. what is the percent of the present cost of this TV will you be saving?
Answered by Penny Nom.
Matrices 2013-11-10
From Ricky:
Why must we have brackets around matrices. Why don't we just neatly write an array of entries cross-wise and up and down to indicate a particular matrix?
Answered by Chris Fisher.
Price, revenue and profit 2013-09-22
From lorraine:
What price maximizes revenue? What price maximizes profit?

The only data I'm given is total output, total revenue, and total cost. I'm not sure how to set up a formula

Answered by Penny Nom.
What is the original price? 2013-04-25
From Dylan:
shirts on sale for 25% off, the sale price is 12.75. What is the original price?
Answered by Penny Nom.
Markup and discount to get a sale price 2013-03-02
From Warren:

If you are an ardent shopper you will be aware of the discount (% decrease) marketing strategy to produce the sale price. I began to wonder just how much mark-up (% increase) was added initially to an item in order to deliver the discounted sale price.

It was simple to construct a formula to convert one to the other.

For example a 30% (mark down) decrease in price required a 42.86% (mark up) to increase the price initially to Tag price. However when I started apply the formulae to a number of circumstances I noticed some very interesting circumstances associated with this relationship

For example a 99.999999% decrease is numerically equal to a 9,999,999,925% increase (huge ratio difference) while conversely a 0.1% decrease is numerically equal to a 0.10010010% increase (Infinitesimally small ratio difference) so the patterns appears logarithmic not linear.

However what really caught my attention was this pattern

See http://www.ozsmart.com/doc/percentage.htm

My questions is why does the decline in the ratio of increases in required mark up (%) price peak at 50 and 51% precisely and then expand again as the percentage move higher

Any explanation would be appreciated

Answered by Harley Weston.
Your profit should be 20% of your cost 2013-02-21
From anis:
if the customer says your profit should be 20% of your cost..

1) my selling value should be cost +20% of cost = SP


2)cost / 0.80 = SP which is correct...if the second answer is right how should i justify my customer

Answered by Penny Nom.
What is the better price? 2012-03-30
From john:
What is the better price?
If a bag of mulch sells for $6.75 and contains 2.7 cubit feet versus a bag selling for $5.99 and contains 2 cubit feet.
Which is the better value?

Answered by Penny Nom.
The price per square inch of a pizza 2012-03-17
From jordan:
pizzaz pizza sells a small pizza for $10.99.it has a diameter 10 inches.what is th price per square inch ?
Answered by Penny Nom.
What was the cost price of the article? 2011-11-10
From tashana:
By selling an article for $320,the profit was 20% of the cost price.what was the cost price of the article.
Answered by Penny Nom.
Geocaching 2010-10-15
From Clint:
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] = ?

Answered by Stephen La Rocque.
Selling price, cost and profit 2010-06-22
From Alex:
The profit on a certain television set is 16.5% of the cost price. If the profit is $330, Find:
a) the cost price
b)the selling price of the television

Answered by Penny Nom.
The price before tax 2010-02-15
From dawn:
the sale tax on a cape was 6%,and total price with tax was $92.75,what was the price of the cape?
Answered by Penny Nom.
Find the original price 2009-11-06
From Cyndy:
Find the original price of a pair of shoes if the sale price is $98.00 after a 30% discount.
Answered by Penny Nom.
Commodity price increase 2009-11-04
From bharat:
if price of a commodity increases by x% the to keep the expenditure same the decrease in consumption should be (x/(x+100))*100, why?
Answered by Penny Nom.
A trillion grains of rice 2009-09-14
From akaila:
can 1trillion rice grains fit in a classroom with the area of 144.4m3
Answered by Penny Nom.
Price increases and decreases 2009-09-02
From craig:
I work for an industry that bases it price increases and decreases on commodity pricing - Customer get confused on how/why we calculated new prices due to movement in the market - Price go up x% for every $10 of movement in the market -

For this example-
Movement went down by $30 and it is 2% for every $10 - so price decrease was 6%.
Customer's price is currently $100.
We say - $100/1.06= new price of $94.3
Customer says - $100*.94= new price of $94.

They don't understand that if board went back up $30 which would be 6% increase, they wouldn't be back at $100 if they multiplied on the price decrease.
$94*1.06=$99.64 vs. $94.3*1.06=$100 (Back to the original price)

What is the best way to explain to customer besides using this example?

Any help or info is appreciated.


Answered by Victoria West.
Percentage price change 2009-08-27
From alicia:
what is the percentage price change between R66-R10 if the answer between the two is R56
Answered by Penny Nom.
Torricelli's trumpet 2009-07-29
From Gary:
I was reading about torricelli's trumpet which is described by the equation1/x which is then rotated around the x axis which results in a figure which looks like a trumpet. Now in order to find the volume the integral 1/x^2 dx is used which diverges when integrated so the volume is finite.However if you integrate 1/x dx which is the formula on the plane the answer diverges. Now if you took an infinite area then rotated it around the x axis shouldn't you get an infinite volume? Notice the area I am talking about is under the line 1/x not the surface area of the trumpet which is what the painters paradox is about What am I missing? Thanks
Answered by Robert Dawson.
The retail price for an ice cream scoop 2009-07-05
From Patricia:
Hi - I am trying to figure out the fairest retail price for an ice cream scoop. We have an ice cream parlor and the cost of the ice cream we buy by the bulk container has recently been increased so now we must charge more for our scoops. We pay a wholesale price of $25.40 for 242 ounces of ice cream. The cost per ounce is $0.105. What is the formula for figuring out how much to charge retail per scoop? This is probably so simple but confusing to me. Please help. Thank you!
Answered by Harley Weston.
Unit Price 2009-06-08
Question from Matt: I quoted my customer $112.50 per 1,000 sheets per linear yards. My client said I was to high. I need to be at 18 cents per square inch. If I matched his 18 cents per square ines what would my linear yards per 1,000 sheets price be? It comes on a 12.5 inch roll.
Answered by Janice Cotcher.
Grain of rice on a chess board 2009-03-30
From andy:
Is there an easy way for my students to find out 8 to the power of 21 to solve the grains of rice doubling investigation on a chessboard? Any suggestions welcome. Thanks very much
Answered by Robert Dawson and Claude Tardif.
Find the retail price 2009-03-18
From Allie:
If you have food that costs $0.75 per portion and your food cost is 16.5% how would you find the retail price?
Answered by Penny Nom.
The column space of a matrix 2009-02-12
From John:
Question from John, a student:


1 1 0 0
1 1 0 0
0 0 1 0
0 0 1 1


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?
Answered by Harley Weston.

Calculating markup 2009-02-03
From Tonya:
I'm trying to figure out the formula for the following, I have a product that I want to receive a certain profit, but with this product I also have to pay a percentage of commission to someone. I need to know how to calculate my new selling price taking into account the markup percentage, but I don't want my cut to be lowered. I have calculated the markup percentage to get my new selling price with the commission, but it lowers my cut once I pay the commission and I don't want it to do that. Thanks
Answered by Penny Nom.
PST and GST 2009-01-20
From janet:
Hello I need to figure what one would pay pst 8% gst 5% on a total of $1700.00 I have a small business some pay with cash I need to calculate the taxes in reverse Can you help with formula that the government might like Thank you Janet
Answered by Harley Weston.
A price reduction and a discount 2008-09-11
From Rita:
A store advertises that during its Labor Day sale $15 will be deducted from every purchase over $100. In addition, after the deduction is taken, the store offers an early-bird discount of 20% to any person who makes a purchase before 10 a.m. If Hakeem makes a purchase of x dollars, x > 100, at 8 a.m., what, in terms of x, is the cost of Hakeem's purchase?

(1) 0.20x - 15 (3) 0.85x - 20
(2) 0.20x -3 (4) 0.80x - 12

Answered by Penny Nom.
The selling price 2008-09-04
From Robert:
Client wants to sell his property providing he is left with 100000.00$ net. How do I calculate selling price if commission is 6% and taxes on the commission 6% Fed and 7.5%prov. I'm taking the real estate class and this one really got me.
Answered by Penny Nom.
A linear system 2008-08-23
From dipesh:
consider the system of equations
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

Answered by Penny Nom.
What is the GST component? 2008-06-11
From Jilly:
I need to find a quick and easy formula for finding the gst (10%) of the total amount in $ terms, eg: the total is $500 what is the gst component?
Answered by Penny Nom.
Calculating a price based on markup 2008-06-03
From Sheldon:
I know the most common form for retail businesses of calculating a price based on markup is: Cost/(1 - Markup), but how is this supposed to work for a business that desires a markup of over 100%.
Answered by Harley Weston.
Selling price 2008-05-10
From Roxane:
I'm trying to figure out the formula for the following, I have a product that I want to receive a certain profit margin, but with this product I also have to pay a percentage of commission to someone. I need to know how to calculate my new selling price taking into account the markup percentage, but I don't want my gross margin to be lowered. I have calculated the markup percentage to get my new selling price with the commission, but it lowers my profit margin once I pay the commission and I don't want it to do that.
Answered by Penny Nom.
Determinants 2008-05-02
From Henry:
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?

Answered by Harley Weston.
Matrix multiplication 2008-04-08
From manashi:
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?

Answered by Harley Weston.
Actural cost, selling price and commission 2008-02-21
From LiSa:
I have a question about a few things if anyone can answer... ex. actual cost (AC) = $1000 selling price (SP) = $ amount earned for company (C) = 15% of... selling price? commission 1 (C1) = 2.5% commission 2 (C2) = 2.5% How would you calculate how much the company's commission amount would be as well as the amounts for the other 2 that get 2.5%? And what would the selling price be? (the 15% $ + 2.5% $ + 2.5% $ ?) Is the 2.5% taken from the original amount? I am soooo confused! If anyone could help, that would be great!
Answered by Harley Weston.
The best price for topsoil 2007-11-15
From Dawn:
What is a better deal for topsoil, $150.00 for 10 cubic yards, $170.00 for 22 tons, or $200.00 for 11.5 yards?
Answered by Penny Nom.
Twenty dining tables 2007-08-13
From priya:
Utkarsh bought 20 dining tables for Rs 120000 and sold these at a profit equal to the S.P of 4 dining tables.Find the S.P of one dining table.(give the answer in statements)
Answered by Stephen La Rocque.
Discount percentage 2007-07-11
From Greg:
List Price: $50.00 Discount: 33 1/3% What would the net price be?
Answered by Stephen La Rocque.
A margin of 19% 2007-02-01
From Ed:
Answered by Penny Nom.
What is the original cost? 2006-04-19
From Charlie:
Selling a piece of furniture for $670 and the profit is 35%. What is the original cost?
Answered by Stephen La Rocque.
What is the cost price? 2006-04-14
From Purushotham:
If the selling price is 120 and the profit is 20%, what is the cost price?
Answered by Stephen La Rocque.
Price percentages 2006-04-13
From Kristine:
An item that is no longer on sale at "25% off" receives a price tag that is 33 1/3% more than the sale price. Has the item price been restored to its original price? Why or Why not?
Answered by Stephen La Rocque.
List price plus 10% 2006-04-03
From Heather:
We shipped 2 pieces of an item with a unit price of $578.74 for a total amount of $1157.48. My task is to bill the customer at LIST + 10%. What formula do I need to use to calculate this?
Answered by penny Nom.
Who is taller: John or Mary? 2005-09-14
From Ulises:
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?
Answered by Penny Nom and Claude Tardif.
Cost price 2005-05-25
From Sunitha:
What is (how to calculate) the cost price of a product which is marked-up by 15% and retailed at $25?
Answered by Penny Nom.
A matrix problem 2005-04-04
From Alan:
Let A = 1-10

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.]

Answered by Judi McDonald.
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.
The price of a book 2004-09-18
From Dorly:
If the number of toonies required to buy a book is nine more than the number of five-dollar bills required to buy the same book, determine the cost of the book.
Answered by Penny.
Arrays 2004-02-19
From A parent:
please demonstrate mathematical arrays fro a 3rd grader
Answered by Penny Nom.
Matrices 2003-12-05
From Julie:
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?
Answered by Judi McDonald.
The mean house price 2003-09-10
From Carol:

I have to find the mean from the following example:

Price Range 000 No of Houses
55 and under 60 3
60 and under 65 6
65 and under 70 13
70 and under 80 21
80 and under 100 15
100 and under 130 7
130 upwards 1

I know when calculating the mean you use the mid points of the classes, but how does this work for the 130 upwards class? Also, does this still work given the difference in the classes (ie. 1st class is 5, 5th class is 20, etc). Any help to get me started would be greatly appreciated.

Answered by Penny Nom.
An onsale DVD player 2003-07-09
From Kim:
I have a DVD player with a regular selling price of $175 and percentage of discount is 10 percent. How to solve for discount amount and sale price? Also, when you figure out the sale price how to figure out commission amount when percentage of commission is 5 percent?
Answered by Penny Nom.
A determinant 2003-02-13
From A student:

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

Answered by Penny Nom.
A house's selling price 2002-11-05
From Tanisha:
Answered by Penny Nom.
A sale price 2002-10-15
From Chester:
A jacket is on sale for 32% off. Find the original if the sale price is $89.00
Answered by Penny Nom.
A sale on eggs 2002-01-17
From A student:
A store had a sale on eggs, selling 13 eggs for the usual price of a dozen eggs. As a result, the price of the eggs was reduced by 4 cents a dozen. What is the original price for a dozen eggs?
Answered by Penny Nom.
Matrix 2001-11-21
From Hoda:
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?
Answered by Patrick Maidorn and Penny Nom.
Conformable matrices 2001-08-05
From Wayne:
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!
Answered by Steve Kirkland.
Matrix reconstruction 2001-07-19
From Guy:
Is there a way to get the sums of rows, columns and diagonals of an n x n matrix to reconstruct the original matrix?
Answered by Walter Whiteley and Patrick Maidorn.
Oil revenue 2001-04-21
From Brian:
Suppose that t months from now an oil well will be producing crude oil at the rate of r(t), not a constant, barrels per month and that the price of crude oil will be p(t), not a constant, dollars per barrel. Assume that the oil is sold as soon as it is extracted from the ground.
  1. Find an expression for the total revenue from the oil well, R(t).

  2. A certain oil well that currently yields 400 barrels of crude oil a month will run dry in 2 years. The price of crude oil is currently $18 per barrel and is expected to rise at a constant rate of 3 cents per barrel per month. What will be the total revenue from this well? {Hint: Model the degraded production rate with the equation:
    r(t) = (A-Bt)e0.04t}

Answered by Harley Weston.
Matrices 2001-03-26
From Peg:
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.
Answered by Judi McDonald and Walter Whiteley.
Solving Equations 2001-02-23
From Stephanie:
Do you know who came up with solving equations?
Do you have any web-sites 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?

Answered by Juci McDonald.
The city transit system 2001-01-07
From Jacky:
The city transit system carries an average of 9450 bus riders a day, for a fare of $1.75 each. The city wants to reduce car pollution by increasing ridership and to maximize the transit system's revenue at the same time. A survey indicates that the number of riders will increase by 150 for every $0.05 decrease in fare.
Answered by Harley Weston.
Where will we use this in the real world? 2000-10-11
From Jane Ann Musgrove:
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.

Answered by Harley Weston.
A matrix equation 2000-05-14
From A student:
Right now, we are dealing with matrices and we are supposed to solve the following problem on our graphing-calculators: 2a+3b-4c+d=20

Answered by Penny Nom.
Matrices Information 2000-05-02
From William Avery :
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:

Answered by Marley Weston.
Taxis in Chicago 2000-03-27
From A high school student high school student:
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?
Answered by Harley Weston.
Matricies 1998-11-26
From Stephanie Webster:
If a matrix for a rectangle looks this way:
    AACC    BDDB 
What does the matrix for a square look like?

Answered by Penny Nom.
Mathematical Arrays 1998-05-01
From Gene Lanctot:
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.
Answered by Harley Weston.
Matrices 1998-03-10
From Ksya:
  1. 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 ???

  2. 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???

Answered by Doug Farenick.
Matrice 2006-02-01
From Kader:
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
Answered by Claude Tardif.
probleme de matrice 2006-02-01
From Un eleve:
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.
Answered by Claude Tardif.
La bissectrice de l'angle ABC 2000-02-16
From Laurent Gauthier:
Est-ce redondant d'ecrire "angle ABC" avec un accent circonflexe sur le B? Peut-on ou devrait-on se contenter d'ecrire soit ABC (avec l'accent), soit l'angle ABC (sans accent) ? Le contexte dans lequel ceci apparait est le syntagme "la bissectrice de l'angle ABC", c'est-a-dire que je me demande si on devrait ecrire "la bissectrice ABC " (avec accent), "la bissectrice de l'angle ABC" (sans accent) ou "la bissectrice de l'angle ABC" (avec accent).
Answered by Claude Tardif.



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