Query 21

#$&*

course Mth 151

021. `query 21

*********************************************

Question: `q4.4.6 star operation [ [1, 3, 5, 7], [3, 1, 7, 5], [5, 7, 1, 3], [7, 5, 3, 1]]

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

Okay I am not sure where this came from. I don’t know what to do. So sorry!!!

confidence rating #$&*:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

`a** Using * to represent the operation the table is

* 1 3 5 7

1 1 3 5 7

3 3 1 7 5

5 5 7 1 3

7 7 5 3 1

the operation is closed, since all the results of the operation are from the original set {1,3,5,7}

the operation has an identity, which is 1, because when combined with any number 1 doesn't change that number. We can see this in the table because the row corresponding to 1 just repeats the numbers 1,3,5,7, as does the column beneath 1.

The operation is commutative--order doesn't matter because the table is symmetric about the main diagonal..

the operation has the inverse property because every number can be combined with another number to get the identity 1:

1 * 1 = 1 so 1 is its own inverse;

3 * 3 = 1 so 3 is its own inverse;

5 * 5 = 1 so 5 is its own inverse;

7 * 7 = 1 so 7 is its own inverse.

This property can be seen from the table because the identity 1 appears exactly once in every row.

the operation appears associative, which means that any a, b, c we have (a * b ) * c = a * ( b * c). We would have to check this for every possible combination of a, b, c but, for example, we have (1 *3) *5=3*5=7 and 1*(3*5)=1*7=7, so at least for a = 1, b = 3 and c = 5 the associative property seems to hold. **

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Self-critique (if necessary):

I am truly lost, I understand how you came to the table, I see how you got the one thing, but I have no clue how you got the rest.

------------------------------------------------

Self-critique Rating:

@& The table shows you how to find the results

1 * 1

1 * 3

1 * 5

1 * 7

3 * 1

3 * 3

3 * 5

3 * 7

5 * 1

5 * 3

5 * 5

5 * 7

7 * 1

7 * 3

7 * 5

7 * 7

where * stands for the 'star' operation, not for standard multiplication.

What are these results?

Is every result in the set {1, 3, 5, 7}?

If so, then the operation is closed.

Is there a number in the set which, when combined with 1, gives you 1; when combined with 3 gives you 3; when combined with 5 gives you 5; and when combined with 7 gives you 7? If so, then this number, which when combined with another number always gives you that number, is the identity.

Is 1 * 3 equal to 3 * 1?

Is 1 * 5 equal to 5 * 1?

Does the same thing work for every pair of numbers in the set? That is, does every possible pair of numbers from the set {1, 3, 5, 7} give the same result in both orders?

If so, then the operation is commutative.

Are there pairs of numbers which, when combined give you the identity?

If so, can every number in the set be combined with another number in the set (possible with itself) to give you the identity?

If so every such pair of numbers is a pari of inverses, and the operation has the inverse property.

See what you think and get back to me on this.*@

*********************************************

Question: `q4.4.24 a, b, c values that show that a + (b * c) not equal to (a+b) * (a+c).

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

Why is this so confusing? I have no idea how to even start this or what to do with this question…..

confidence rating #$&*:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

`a** For example if a = 2, b = 5 and c = 7 we have

a + (b + c) = 2 + (5 + 7) = 2 + 12 = 14 but

(a+b) * (a+c) = (2+5) + (2+7) = 7 + 12 = 19. **

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Self-critique (if necessary):

Okay, I didn’t think about added my own numbers or was I suppose to know that I should of picked those numbers!!!!

------------------------------------------------

Self-critique Rating:

@& You get to pick the numbers a, b and c.

You either keep picking until you get three numbers for which a + (b * c) is not equal to (a+b) * (a+c), or you end up checking out every pair to show that the two expressions are always the same.*@

*********************************************

Question: `q4.4.33 venn diagrams to show that union distributes over intersection

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

Once again, I am not even sure how to start this because I don’t recall this being in the chapter.

confidence rating #$&*:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

`a** For A U (B ^ C) we would shade all of A in addition to the part of B that overlaps C, while for (A U B) ^ (A U C) we would first shade all of A and B, then all of A and C, and our set would be described by the overlap between these two shadings. We would thus have all of A, plus the overlap between B and C. Thus the result would be the same as for A U (B ^ C). **

*****Okay this is so unfair, this wasn’t in the chapter and why would I know to do this????? Sorry very frustrated. I thought I was getting the hang of things and then bam, I get confused again. Lol!!!

"

Self-critique (if necessary):

------------------------------------------------

Self-critique rating:

*********************************************

Question: `q4.4.33 venn diagrams to show that union distributes over intersection

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

Once again, I am not even sure how to start this because I don’t recall this being in the chapter.

confidence rating #$&*:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

`a** For A U (B ^ C) we would shade all of A in addition to the part of B that overlaps C, while for (A U B) ^ (A U C) we would first shade all of A and B, then all of A and C, and our set would be described by the overlap between these two shadings. We would thus have all of A, plus the overlap between B and C. Thus the result would be the same as for A U (B ^ C). **

*****Okay this is so unfair, this wasn’t in the chapter and why would I know to do this????? Sorry very frustrated. I thought I was getting the hang of things and then bam, I get confused again. Lol!!!

"

Self-critique (if necessary):

------------------------------------------------

Self-critique rating:

#*&!

*********************************************

Question: `q4.4.33 venn diagrams to show that union distributes over intersection

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

Once again, I am not even sure how to start this because I don’t recall this being in the chapter.

confidence rating #$&*:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

`a** For A U (B ^ C) we would shade all of A in addition to the part of B that overlaps C, while for (A U B) ^ (A U C) we would first shade all of A and B, then all of A and C, and our set would be described by the overlap between these two shadings. We would thus have all of A, plus the overlap between B and C. Thus the result would be the same as for A U (B ^ C). **

*****Okay this is so unfair, this wasn’t in the chapter and why would I know to do this????? Sorry very frustrated. I thought I was getting the hang of things and then bam, I get confused again. Lol!!!

"

@& Chapter 2 covered the properties of union and intersection. This section deals with distributive properties, so this is a reasonable (but challenging) question.

Most students will not get this, but some will.*@

Self-critique (if necessary):

------------------------------------------------

Self-critique rating:

#*&!#*&!

@& See my notes and get back to me on that first problem.*@

*********************************************

Question: `q4.4.33 venn diagrams to show that union distributes over intersection

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

Once again, I am not even sure how to start this because I don’t recall this being in the chapter.

confidence rating #$&*:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

`a** For A U (B ^ C) we would shade all of A in addition to the part of B that overlaps C, while for (A U B) ^ (A U C) we would first shade all of A and B, then all of A and C, and our set would be described by the overlap between these two shadings. We would thus have all of A, plus the overlap between B and C. Thus the result would be the same as for A U (B ^ C). **

*****Okay this is so unfair, this wasn’t in the chapter and why would I know to do this????? Sorry very frustrated. I thought I was getting the hang of things and then bam, I get confused again. Lol!!!

"

@& Chapter 2 covered the properties of union and intersection. This section deals with distributive properties, so this is a reasonable (but challenging) question.

Most students will not get this, but some will.*@

Self-critique (if necessary):

------------------------------------------------

Self-critique rating:

#*&!#*&!

@& See my notes and get back to me on that first problem.*@

#*&!