Assignment 21

course Mth 151

I could not get Assignment 20 to run so I went on to Assignment 21

U`vਫ਼zDZassignment #021

Your work has been received. Please scroll through the document to see any inserted notes (inserted at the appropriate place in the document, in boldface) and a note at the end. The note at the end of the file will confirm that the file has been reviewed; be sure to read that note. If there is no note at the end, notify the instructor through the Submit Work form, and include the date of the posting to your access page.

021. There are thirteen questions in this assignment. Numeration and Operations Liberal Arts Mathematics I 07-30-2007 x뜊乐 assignment #021 021. There are thirteen questions in this assignment. Numeration and Operations Liberal Arts Mathematics I 07-30-2007

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13:26:11 `q001. If we define the operation @ on two numbers x and y by x @ y = remainder when the product x * y is multiplied by 2 then divided by 3, then find the following: 2 @ 5, 3 @ 8, 7 @ 13.

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RESPONSE --> I am moving on to the answer I am unclear on the method. confidence assessment: 0

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13:34:38 By the definition, 2 @ 5 is the remainder when the product 2 * 5 is doubled then divided by 3. We start with 2 * 5 = 10, then double that to get 20, then divide by three. 20 / 3 = 6 with remainder 2. So 2 @ 5 = 2. We follow the same procedure to find 3 @ 8. We get 3 * 8 = 24, then double that to get 48, then divide by three. 48 / 3 = 12 with remainder 0. So 3 @ 8 = 0. Following the same procedure to find 7 @ `2, we get 7 * 13 = 91, then double that to get 182, then divide by three. 182 / 3 = 60 with remainder 2. So 7 @ 13 = 2.

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RESPONSE --> I completely understand now. I was unsure what to do with the remainder. Now I understand clearly. self critique assessment: 3

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13:51:49 `q002. If we define the @ operation from the previous exercise just on the set {5, 6, 7} , we can use the same process as in the preceding solution to get 5 @ 5 = 2, 5 @ 6 = 0, 5 @ 7 = 1, 6 @ 5 = 0, 6 @ 6 = 0, 6 @ 7 = 0, 7 @ 5 = 1, 7 @ 6 = 0 and 7 @ 7 = 2. We can put these results in a table as follows: @ 5 6 7 5 2 0 1 6 0 0 0 7 1 0 2. Make a table for the @ operation restricting x and y to the set {2, 3, 4}.

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RESPONSE --> Solutions: 2@2=2 2@3=0 2@4=1 3@2=0 3@3=0 3@4=0 4@2=1 4@3=0 4@4=2 Table: @ 2 3 4 2 2 0 1 3 0 0 0 4 1 0 2 confidence assessment: 3

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13:52:05 Using the same process as in the solution to the preceding problem we find that 2 @ 2 = 2, 2 @ 3 = 0, 2 @ 4 = 1, 3 @ 2 = 3 @ 3 = 3 @ 4 = 0, 4 @ 2 = 1, 4 @ 3 = 0 and 4 @ 4 = 2. The table is therefore @ 2 3 4 2 2 0 1 3 0 0 0 4 1 0 2.

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RESPONSE --> I answered this correctly self critique assessment: 3

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13:53:36 `q003. All the x and y values for the table in the preceding problem came from the set {2, 3, 4}. From what set are the results x @ y taken?

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RESPONSE --> {x, y} confidence assessment: 0

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13:56:57 The results of the operation x @ y, which ultimately consist of the remainder when some number is divided by 3, must all be division-by-3 remainders. The only possible remainders we can have when dividing by three are 0, 1 or 2. Thus all the results of the operation x @ y are members of the set {0, 1, 2}.

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RESPONSE --> Yes I understand. I misunderstood the question but I know this to be true. self critique assessment: 3

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13:59:05 `q004. Are the results of the operation x @ y on the set {2, 3, 4} all members of the set {2, 3, 4}?

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RESPONSE --> No, all the results of the operation x @ y on the set {2, 3, 4} will be {0,1,2} because in the operation we divided 3. Because of this we know that none of the remainders will be greater than 2. confidence assessment: 3

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13:59:32 The possible results of the operation, whose table is @ 2 3 4 2 1 0 2 3 0 0 0 4 2 0 1 , are seen from the table to be 0, 1 and 2. Of these possible results, only 2 is a member of the set {2,3,4}. So it is not the case that all the results come from the set {2, 3, 4}.

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RESPONSE --> I answered this correctly self critique assessment: 3

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14:02:42 `q005. Since the operation x @ y on the set {2, 3, 4} can result in at least some numbers which are not members of the set, we say that the @operation is not closed on the set {2, 3, 4}. Is the @ operation closed on the set S = {0, 1, 2}? Is the @ operation closed on the set T = {0, 2}? Is the @ operation closed on the set R = {1, 2}?

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RESPONSE --> Is the @ operation closed on the set S = {0, 1, 2}? Yes Is the @ operation closed on the set T = {0, 2}? No because the 1 is not present Is the @ operation closed on the set R = {1, 2}? No because the 0 is not present confidence assessment: 1

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14:06:18 When operating on the set S = {0, 1, 2} the operation must as always give one of the division-by-3 remainders 0, 1 or 2. Thus the results are all in the set S. When operating on the set T = {0, 2} the possible results are 0 @ 0 = 0 @ 2 = 2 @ 0 = 0, or 2 @ 2 = 2. Since the possible results are 0 and 2, both of which are in T, all the results come from the set T on which we are operating, and the operation is closed on the set T. When operating on the set R = {1, 2} the possible results are 1 @ 1 = 2, 1 @ 2 = 2 @ 1 = 1, or 2 @ 2 = 2. Since the possible results are 1 and 2 and both are in the set R, we can say that all the results come from the set R on which we are operating, and the operation is indeed closed on the set R.

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RESPONSE --> I answered the first one correctly but I got the other 2 wrong. I see my error. I thought that is one of the numbers in the set 0, 1, 2 was not present then it made it not closed. I see now that if all the numbers in the set in question are present in the set 0, 1, 2 then it will indeed close the operation. self critique assessment: 3

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14:08:04 `q006. How can we tell by looking at the table whether the operation is closed?

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RESPONSE --> If all the same number 0,1,2 are present and there are no other numbers present. confidence assessment: 1

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14:09:10 If all the numbers in the table come from the far left-hand column of the table--e.g., the column underneath the @ in the tables given above, which lists all the members of the set being operated on --then all the results of the operation are in that set and the operation is therefore closed.

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RESPONSE --> I believe we are trying to say the same thing in different words. self critique assessment: 3

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14:11:38 `q007. When calculating x @ y for two numbers x and y, does it make a difference whether we calculate x @ y or y @ x?

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RESPONSE --> NO, for example if you have the set {2,3} and are calculating x @ y for these two numbers you have to multipily. As we know, 2*3 and 3*2 give the same answer. confidence assessment: 3

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14:13:44 Since the first step in calculating x @ y is to multiply x * y, it would make no difference whether we multiplied x * y or y * x. So in the first step it makes no difference whether we calculate x @ y or y @ x. Since all we do after that is double our result and calculate the remainder when dividing by 3, the order of x and y won't make a difference there either. So we conclude that for this operation x @ y must always equal y @ x. This property of the operation is called the commutative property, meaning roughly that order doesn't matter.

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RESPONSE --> I answered this correctly self critique assessment: 3

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14:15:10 `q008. Does the operation of subtraction of whole numbers have the commutative property?

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RESPONSE --> NO because if you switch the order of two numbers when subtracting you will get a different answer. For example: 4-2=2 but 2-4=-2 confidence assessment: 2

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14:15:36 Subtraction of whole numbers does not have the commutative property, because it is not true for most whole numbers x and y that x - y = y - x. For example, 5 - 3 = 2 while 3 - 5 = -2. So for subtraction order usually does matter, and the operation is not commutative.

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RESPONSE --> I answered this correctly self critique assessment: 3

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14:16:07 `q009. Is the operation of subtraction closed on the set of whole numbers?

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RESPONSE --> NO confidence assessment: 1

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14:16:36 Whole numbers are the numbers in the set {0, 1, 2, 3, ... }. If we subtract a smaller number from a larger, we will again get a whole number. However if we subtract a smaller number from the larger, we will get a negative result, which is not a whole number. Since it is possible to subtract two numbers in the set and to get a result that is not in the set, the operation is not closed.

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RESPONSE --> I answered this correctly self critique assessment: 3

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14:18:16 `q010. Is the operation of addition closed and commutative on the set of whole numbers?

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RESPONSE --> Yes, in addition, like multiplication, it does not matter the order of the numbers you will always get the same answer. confidence assessment: 3

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14:18:51 When we add two numbers x and y it doesn't matter which one we add to which--it doesn't matter whether we do x + y or y + x--so order doesn't matter and we can say that the operation is commutative. And if we add two whole numbers, which must both be at least 0, we get a whole number which is at least 0. So the operation is also closed.

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RESPONSE --> I answered this correctly self critique assessment: 3

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14:20:21 `q011. When we multiply a number by 1, what must be our result?

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RESPONSE --> Our result will alway be the number we are multipling. For example 4*1=4 confidence assessment: 3

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14:20:40 Any number multiplied by 1 will give us the same number. Any number is unchanged if we multiply it by 1. That is 10 * 1 = 10, or -37.27 * 1 = -37.27, or 72 * 1 = 72. Multiplication by 1 does not change any number.

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RESPONSE --> I answered this correctly self critique assessment: 3

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14:27:54 `q012. A number which does not change any number with which it is combined using a certain operation is called the identity for the operation. As we saw in the preceding exercise, the number 1 is the identity for the operation of multiplication on real numbers. Does the operation @ (which was defined in preceding exercises by x @ y = remainder when x * y is doubled and divided by 3) have an identity on the set {0, 1, 2}? Does @ have an identity on the set {0, 2}?

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RESPONSE --> No because 1 is not present. confidence assessment: 3

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14:28:48 The table for @ on {0, 1, 2) is @ 0 2 1 0 0 0 0 1 0 2 1 2 0 1 2. We see from the row across from 2 that 2 * 0 = 0, 2 * 1 = 1 and 2 * 2 = 2. We also see from the column beneath 2 that 0 * 2 = 0, 1 * 2 = 1 and 2 * 2 = 2. Thus, no matter how we combine 2 with other numbers in the set {0, 1, 2}, we don't change those other numbers. That is, for any x in the set, 2 @ x = x @ 2 = x. Therefore @ does indeed have identity 2 on the set {0, 1, 2}. On the set {0, 1} the number 2 isn't included. Since 0 * 1 = 0, not 1, the number 0 can't be the identity. Since 1 * 1 = 2, not 1, the number 1 can't be the identity. Both 0 and 1 at least sometimes change the number they operate with, and the identity can't do this.

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RESPONSE --> I understand self critique assessment: 3

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14:29:46 `q013. Does the set of whole numbers on the operation of addition have an identity?

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RESPONSE --> Yes, because if you add 0 to any number you will get the same number. Example:4+0=4 confidence assessment: 3

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14:30:04 The identity must be a number that doesn't change the number with which it is combined. The number 0 has this property. Whenever we add to 0 is what we get. 0 doesn't change the number it is combined with under the operation of addition. For any x, 0 + x = x and x + 0 = x. Therefore we can say that 0 is the identity for addition on the set of whole numbers.

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RESPONSE --> I answered this correctly self critique assessment: 3

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`gr42

Assignment 21

course Mth 151

I could not get Assignment 20 to run so I went on to Assignment 21

U`vਫ਼zDZassignment #021

Your work has been received. Please scroll through the document to see any inserted notes (inserted at the appropriate place in the document, in boldface) and a note at the end. The note at the end of the file will confirm that the file has been reviewed; be sure to read that note. If there is no note at the end, notify the instructor through the Submit Work form, and include the date of the posting to your access page.

021. There are thirteen questions in this assignment.

Numeration and Operations

Liberal Arts Mathematics I

07-30-2007

x뜊乐

assignment #021

021. There are thirteen questions in this assignment.

Numeration and Operations

Liberal Arts Mathematics I

07-30-2007

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13:26:11

`q001. If we define the operation @ on two numbers x and y by

x @ y = remainder when the product x * y is multiplied by 2 then divided by 3, then find the following:

2 @ 5,

3 @ 8,

7 @ 13.

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RESPONSE -->

I am moving on to the answer I am unclear on the method.

confidence assessment: 0

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13:34:38

By the definition, 2 @ 5 is the remainder when the product 2 * 5 is doubled then divided by 3. We start with 2 * 5 = 10, then double that to get 20, then divide by three. 20 / 3 = 6 with remainder 2. So 2 @ 5 = 2.

We follow the same procedure to find 3 @ 8. We get 3 * 8 = 24, then double that to get 48, then divide by three. 48 / 3 = 12 with remainder 0. So 3 @ 8 = 0.

Following the same procedure to find 7 @ `2, we get 7 * 13 = 91, then double that to get 182, then divide by three. 182 / 3 = 60 with remainder 2. So 7 @ 13 = 2.

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RESPONSE -->

I completely understand now. I was unsure what to do with the remainder. Now I understand clearly.

self critique assessment: 3

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13:51:49

`q002. If we define the @ operation from the previous exercise just on the set {5, 6, 7} , we can use the same process as in the preceding solution to get 5 @ 5 = 2, 5 @ 6 = 0, 5 @ 7 = 1, 6 @ 5 = 0, 6 @ 6 = 0, 6 @ 7 = 0, 7 @ 5 = 1, 7 @ 6 = 0 and 7 @ 7 = 2. We can put these results in a table as follows:

@ 5 6 7

5 2 0 1

6 0 0 0

7 1 0 2.

Make a table for the @ operation restricting x and y to the set {2, 3, 4}.

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RESPONSE -->

Solutions:

2@2=2

2@3=0

2@4=1

3@2=0

3@3=0

3@4=0

4@2=1

4@3=0

4@4=2

Table:

@ 2 3 4

2 2 0 1

3 0 0 0

4 1 0 2

confidence assessment: 3

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13:52:05

Using the same process as in the solution to the preceding problem we find that 2 @ 2 = 2, 2 @ 3 = 0, 2 @ 4 = 1, 3 @ 2 = 3 @ 3 = 3 @ 4 = 0, 4 @ 2 = 1, 4 @ 3 = 0 and 4 @ 4 = 2. The table is therefore

@ 2 3 4

2 2 0 1

3 0 0 0

4 1 0 2.

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RESPONSE -->

I answered this correctly

self critique assessment: 3

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13:53:36

`q003. All the x and y values for the table in the preceding problem came from the set {2, 3, 4}. From what set are the results x @ y taken?

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RESPONSE -->

{x, y}

confidence assessment: 0

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13:56:57

The results of the operation x @ y, which ultimately consist of the remainder when some number is divided by 3, must all be division-by-3 remainders. The only possible remainders we can have when dividing by three are 0, 1 or 2. Thus all the results of the operation x @ y are members of the set {0, 1, 2}.

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RESPONSE -->

Yes I understand. I misunderstood the question but I know this to be true.

self critique assessment: 3

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13:59:05

`q004. Are the results of the operation x @ y on the set {2, 3, 4} all members of the set {2, 3, 4}?

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RESPONSE -->

No, all the results of the operation x @ y on the set {2, 3, 4} will be {0,1,2} because in the operation we divided 3. Because of this we know that none of the remainders will be greater than 2.

confidence assessment: 3

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13:59:32

The possible results of the operation, whose table is

@ 2 3 4

2 1 0 2

3 0 0 0

4 2 0 1

, are seen from the table to be 0, 1 and 2. Of these possible results, only 2 is a member of the set {2,3,4}. So it is not the case that all the results come from the set {2, 3, 4}.

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RESPONSE -->

I answered this correctly

self critique assessment: 3

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14:02:42

`q005. Since the operation x @ y on the set {2, 3, 4} can result in at least some numbers which are not members of the set, we say that the @operation is not closed on the set {2, 3, 4}.

Is the @ operation closed on the set S = {0, 1, 2}? Is the @ operation closed on the set T = {0, 2}? Is the @ operation closed on the set R = {1, 2}?

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RESPONSE -->

Is the @ operation closed on the set S = {0, 1, 2}? Yes

Is the @ operation closed on the set T = {0, 2}? No because the 1 is not present

Is the @ operation closed on the set R = {1, 2}? No because the 0 is not present

confidence assessment: 1

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14:06:18

When operating on the set S = {0, 1, 2} the operation must as always give one of the division-by-3 remainders 0, 1 or 2. Thus the results are all in the set S.

When operating on the set T = {0, 2} the possible results are 0 @ 0 = 0 @ 2 = 2 @ 0 = 0, or 2 @ 2 = 2. Since the possible results are 0 and 2, both of which are in T, all the results come from the set T on which we are operating, and the operation is closed on the set T.

When operating on the set R = {1, 2} the possible results are 1 @ 1 = 2, 1 @ 2 = 2 @ 1 = 1, or 2 @ 2 = 2. Since the possible results are 1 and 2 and both are in the set R, we can say that all the results come from the set R on which we are operating, and the operation is indeed closed on the set R.

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RESPONSE -->

I answered the first one correctly but I got the other 2 wrong. I see my error. I thought that is one of the numbers in the set 0, 1, 2 was not present then it made it not closed. I see now that if all the numbers in the set in question are present in the set 0, 1, 2 then it will indeed close the operation.

self critique assessment: 3

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14:08:04

`q006. How can we tell by looking at the table whether the operation is closed?

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RESPONSE -->

If all the same number 0,1,2 are present and there are no other numbers present.

confidence assessment: 1

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14:09:10

If all the numbers in the table come from the far left-hand column of the table--e.g., the column underneath the @ in the tables given above, which lists all the members of the set being operated on --then all the results of the operation are in that set and the operation is therefore closed.

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RESPONSE -->

I believe we are trying to say the same thing in different words.

self critique assessment: 3

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14:11:38

`q007. When calculating x @ y for two numbers x and y, does it make a difference whether we calculate x @ y or y @ x?

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RESPONSE -->

NO, for example if you have the set {2,3} and are calculating x @ y for these two numbers you have to multipily. As we know, 2*3 and 3*2 give the same answer.

confidence assessment: 3

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14:13:44

Since the first step in calculating x @ y is to multiply x * y, it would make no difference whether we multiplied x * y or y * x. So in the first step it makes no difference whether we calculate x @ y or y @ x. Since all we do after that is double our result and calculate the remainder when dividing by 3, the order of x and y won't make a difference there either.

So we conclude that for this operation x @ y must always equal y @ x.

This property of the operation is called the commutative property, meaning roughly that order doesn't matter.

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RESPONSE -->

I answered this correctly

self critique assessment: 3

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14:15:10

`q008. Does the operation of subtraction of whole numbers have the commutative property?

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RESPONSE -->

NO because if you switch the order of two numbers when subtracting you will get a different answer. For example: 4-2=2 but 2-4=-2

confidence assessment: 2

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14:15:36

Subtraction of whole numbers does not have the commutative property, because it is not true for most whole numbers x and y that x - y = y - x. For example, 5 - 3 = 2 while 3 - 5 = -2. So for subtraction order usually does matter, and the operation is not commutative.

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RESPONSE -->

I answered this correctly

self critique assessment: 3

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14:16:07

`q009. Is the operation of subtraction closed on the set of whole numbers?

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RESPONSE -->

NO

confidence assessment: 1

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14:16:36

Whole numbers are the numbers in the set {0, 1, 2, 3, ... }. If we subtract a smaller number from a larger, we will again get a whole number. However if we subtract a smaller number from the larger, we will get a negative result, which is not a whole number. Since it is possible to subtract two numbers in the set and to get a result that is not in the set, the operation is not closed.

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RESPONSE -->

I answered this correctly

self critique assessment: 3

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14:18:16

`q010. Is the operation of addition closed and commutative on the set of whole numbers?

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RESPONSE -->

Yes, in addition, like multiplication, it does not matter the order of the numbers you will always get the same answer.

confidence assessment: 3

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14:18:51

When we add two numbers x and y it doesn't matter which one we add to which--it doesn't matter whether we do x + y or y + x--so order doesn't matter and we can say that the operation is commutative.

And if we add two whole numbers, which must both be at least 0, we get a whole number which is at least 0. So the operation is also closed.

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RESPONSE -->

I answered this correctly

self critique assessment: 3

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14:20:21

`q011. When we multiply a number by 1, what must be our result?

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RESPONSE -->

Our result will alway be the number we are multipling. For example 4*1=4

confidence assessment: 3

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14:20:40

Any number multiplied by 1 will give us the same number. Any number is unchanged if we multiply it by 1. That is 10 * 1 = 10, or -37.27 * 1 = -37.27, or 72 * 1 = 72. Multiplication by 1 does not change any number.

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RESPONSE -->

I answered this correctly

self critique assessment: 3

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14:27:54

`q012. A number which does not change any number with which it is combined using a certain operation is called the identity for the operation. As we saw in the preceding exercise, the number 1 is the identity for the operation of multiplication on real numbers.

Does the operation @ (which was defined in preceding exercises by x @ y = remainder when x * y is doubled and divided by 3) have an identity on the set {0, 1, 2}? Does @ have an identity on the set {0, 2}?

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RESPONSE -->

No because 1 is not present.

confidence assessment: 3

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14:28:48

The table for @ on {0, 1, 2) is

@ 0 2 1

0 0 0 0

1 0 2 1

2 0 1 2.

We see from the row across from 2 that 2 * 0 = 0, 2 * 1 = 1 and 2 * 2 = 2. We also see from the column beneath 2 that 0 * 2 = 0, 1 * 2 = 1 and 2 * 2 = 2. Thus, no matter how we combine 2 with other numbers in the set {0, 1, 2}, we don't change those other numbers. That is, for any x in the set, 2 @ x = x @ 2 = x.

Therefore @ does indeed have identity 2 on the set {0, 1, 2}.

On the set {0, 1} the number 2 isn't included. Since 0 * 1 = 0, not 1, the number 0 can't be the identity. Since 1 * 1 = 2, not 1, the number 1 can't be the identity. Both 0 and 1 at least sometimes change the number they operate with, and the identity can't do this.

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RESPONSE -->

I understand

self critique assessment: 3

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14:29:46

`q013. Does the set of whole numbers on the operation of addition have an identity?

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RESPONSE -->

Yes, because if you add 0 to any number you will get the same number.

Example:4+0=4

confidence assessment: 3

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14:30:04

The identity must be a number that doesn't change the number with which it is combined. The number 0 has this property. Whenever we add to 0 is what we get. 0 doesn't change the number it is combined with under the operation of addition. For any x, 0 + x = x and x + 0 = x. Therefore we can say that 0 is the identity for addition on the set of whole numbers.

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RESPONSE -->

I answered this correctly

self critique assessment: 3

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Your work looks very good. Let me know if you have any questions. &#