Question

@mathstudent55 @amistre64 @ganeshie8 @thomaster

For which operations is the set {–1, 0, 1} closed?

Choose all answers that are correct.

A.
addition

B.
division

C.
multiplication

D.
subtraction

Answer 1

can you tell me the definition of closed?

Answer 2

Not sure what it is asking, but if I am assuming that by closed it means equal to zero, then it would be Addition.

Answer 3

consider when something is closed, or locked, nothing new can get in, and nothing old can get out .....

Answer 4

i think it is multipication

Answer 5

multiplicaiton works

Answer 6

if we have a closed set: {a,b,c}

then for an operation, O, to be closed on the set: xOy is also in the set

Answer 7

for any x,y in the set

Answer 8

but it is more than one answer

Answer 9

a set is closed under an operation if whenever you operate on two members of the set, the result of the operation is also in the set.

Answer 10

A.
addition 1+1 = 2

B.
division 1/0 = ?

C.
multiplication

D.
subtraction -1-1 = -2

Answer 11

it cant be more than one answer ....

Answer 12

Choose all answers that are correct. it says

Answer 13

so choose all the answer that are correct

Answer 14

you dont need to do all the permutation, if one of them fails than its not closed.

Answer 15

if you cant think of a fail, testing out the permutes is viable

Answer 16

5000 medals wow @mathstudent55

Answer 17

so just go with multipication

Answer 18

yes, its the only one that works

Answer 19

Don't exaggerate; I only have 4604 so far.

Answer 20

it is ALL the correct ones lol

Answer 21

LOL

Answer 22

I thought that title was earned at 5000 sorry

Answer 23

well 1 + 1 = 2 (unless its modulo 2 addition)

Answer 24

only C works , if we have base 10 addition, subtraction, addition, multiplication

Answer 25

@perl You are correct. A number can be paired with itself, so 1 + 1 has to be included. There are 9 operations that need to be checked for each of addition, subtraction, multiplication, and division.

Answer 26

the question is a tiny bit ambiguous since it does not state what kind of addition it is (it could be modulo 2 addition) .

Answer 27

what is modulo 2 addition?

Answer 28

thx @mathstudent55

Answer 29

modulo addition is like having a clock with only two digits , 0 and 1

Answer 30

oh I see, so its basically like limitations when graphing?

Answer 31

you are probably more accustomed to using modulo 12 time

Answer 32

Ah yes I see now, just wikid it.

Answer 33

but it doesn't look like its directly relevant to the question

Answer 34

true true, what math course uses the modular arithmetic stuff?