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 @geerky42 @zzr0ck3r @tommynaiter

Answer 2

is 1+1 in the set?

Answer 3

is 1-1 in the set?

Answer 4

is -1*-1=1, -1*1=-1 all in the set?

Answer 5

I'm so confused

Answer 6

is -1/1 and 1/1 and -1/-1 and 1/-1 in the set?

Answer 7

What does ion the set mean? what makes something in the set?

Answer 8

a set is closed wrt operation if for any 2 elements in the set, the result of the operation on those 2 elements is in the set

Answer 9

since 1 and 1 are both in the set, and 1+1 = 2 is not. The set is NOT closed with respect to addition

Answer 10

similarly 1-1 = 0 is not in the set, so it is not closed with respect to subtraction.

Answer 11

what about multiplication?

Answer 12

ohh I get it

Answer 13

So it's not closed with subtraction

Answer 14

or addition

Answer 15

correct

Answer 16

but it is for multipplication

Answer 17

correct

Answer 18

And division

Answer 19

right, does it still work for division if we throw in 0?

Answer 20

or any other number?

Answer 21

no

Answer 22

?

Answer 23

correct, say we throw in 3, then we need 1/3 and then we need (1/3)/3 = 1/9...

Answer 24

Thank you! were so helpful!

Answer 25

np