Question

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

Choose all answers that are correct.

A.
addition

B.
subtraction

C.
multiplication

D.
division

Answer 1

@ganeshie8

Answer 2

multiplication only

Answer 3

are you sure?

Answer 4

actually no

Answer 5

let me check one more time

Answer 6

Ok well addition its obvious its not closed since 1+1=2
Subtraction its not closed since -1-1=-2
Division is not closed since 1/0=undefined
So multiplication is the only one that is closed

Answer 7

ok so you clarified mine so just multiplication

Answer 8

Hmmm is this set include all real numbers or just integers?

Answer 9

Anyways ya its just multiplication

Answer 10

Which equations show that the set of whole numbers is not closed under subtraction?

Choose all answers that are correct.

A.
1 – (–2) = 3

B.
1 – 2 = –1

C.
2 – 0 = 2

D.
2 – 4 = –2

Answer 11

but @Mimi_x3 we don't have to worry about 0 since it is not in {-1,1}

Answer 12

so it is both division and multiplication

Answer 13

well all we have is 1 and -1 so it would be just multiplication

Answer 14

Welll freckles if its an interval then it includes 0
Thats my question ... is this an interval or is this just a set with 2 values including 1 and -1?

Answer 15

{-1,1} isn't an interval

Answer 16

ohhhh i seee {-1,1} it just intervals ... not wearing my glasses

Answer 17

K thanks :)

Answer 18

so its both multiplication and division?

Answer 19

Yes

Answer 20

OK that would work i guess

Answer 21

yes because
(-1)(1)=-1 and 1(1)=1 and (-1)(-1)=1 and 1(-1)=-1
all of these outputs are in {-1,1}

just like we take any two numbers from the set and do all the possible divisions all the outputs will also be in {-1,1}
like so:
-1/1=-1 and 1/1=1 and -1/-1=1 and 1/-1=-1

Answer 22

since 1/1=1
1/-1=-1

Answer 23

oh i understand know,thanks!

Answer 24

if it was {-1,0,1}
you guys would have nailed it

Answer 25

oh yeah that would make scenes why i thought it was that.i had that question on a test 2 days ago.