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Matrice |
2006-02-01 |
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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. |
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probleme de matrice |
2006-02-01 |
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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. |
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The box of maximum volume |
2006-02-01 |
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From Elizabeth:
A box factory has a large stack of unused rectangular cardboard sheets with the dimensions of 26 cm length and 20 cm width.
The question was to figure what size squares to remove from each corner to create the box with the largest volume.
I began by using a piece of graph paper and taking squares out. I knew that the formula L X W X H would give me volume. After trial and error of trying different sizes I found that a 4cm X 4cm square was the largest amount you can take out to get the largest volume. My question for you is two parts
First: Why does L X H X W work? And second, is their a formula that one could use, knowing the length and width of a piece of any material to find out what the largest possible volume it can hold is without just trying a bunch of different numbers until you get it. If there is, can you explain how and why it works.
Answered by Penny Nom. |
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The sum of two numbers is 21. |
2006-01-31 |
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From Dan:
The sum of two numbers is 21. One number is three less than the other. Find the numbers
Answered by Penny Nom. |
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What is 3.5% of 4000.00? |
2006-01-31 |
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From Ellen:
What is 3.5% of 4000.00?
What is 3.5% of 2000.00?
Answered by Penny Nom. |
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BEDMAS |
2006-01-31 |
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From Janielle:
What Do All the Letters In BEDMAS Stand for?
Answered by Penny. |
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Arithmetic progressions |
2006-01-31 |
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From A student:
1)the sum to n terms of a particular series is given by Sn=17n-3n2
a)find an expression for the n term of the series
b)show that the series is an arithmetic progression
2)a particular arithmetic progression has a positive common difference and is such that for any three adjacent terms ,three times the sum of their squares exceeds the square of their sum is 375.Find the common difference
Answered by Penny Nom. |
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Make 2 rows of 4 circles with only 6 circles |
2006-01-31 |
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From Sarah:
Moving as many circles as you need, make 2 rows of 4 circles only having 6 circles?
Answered by Chris Fisher. |
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An array problem |
2006-01-31 |
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From Cynthia:
Write a number sentence for this array........
It's a rectangle box 3 down and 4 wide.
Answered by Penny Nom. |
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Counting digits |
2006-01-30 |
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From Cynthia:
I would like to know the easiest way to calculate the
total numbers of digits used by a printer to number the pages of a book from 1 to 250.
Answered by Penny Nom. |
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Write the array for 3 |
2006-01-29 |
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From Jamie:
My son is a 5th grader and came home with a math question that I can't answer. The question stated - "Write the array for 3" I don't understand how this can be done with just one number.
Answered by Penny Nom. |
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Percentage increase in sound intensity |
2006-01-29 |
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From David:
I am doing some emotion response mapping.
Being a composer I know how to push the heart beat tempo by a % increase of BPM in my music. I want to know how to calculate an increase in intensity of sound. Now I have 60 decibels. I want an increase of intensity by a factor n% with out going over 156 decibels.
Answered by Penny Nom. |
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Cubic yards of dirt |
2006-01-28 |
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From Greg:
How many yards of dirt do i need to cover an area of 1000 ft long, 20 ft wide and 3 inches deep
Answered by Penny Nom. |
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How much will each piece weigh? |
2006-01-28 |
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From Matt:
How many equal pieces that weigh between 12 and 13 ounces can be made from 110 ounce block if the whole block is used? How much will each piece weigh?
A paper square has area of 100 in2. Into how many pieces of equal area must the square be but if the area of each piece is to be between 8 in2 and 9 in2? What is area of piece?
Answered by Penny Nom. |
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Word problems |
2006-01-27 |
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From Duk:
One kind of candy sells for 90cents more a pound than another kind. A pound of each sells for a total of $5.10. What is the selling price of each kind?
A soft drink sells for 20 cents more than the deposit required on the bottle. The cost of the soft drink and the bottle deposit totals 70cents. How much is the soft drink? The bottle deposit?
Answered by Penny Nom. |
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