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

Choose all answers that are correct.

A.

addition

B.

subtraction

C.

multiplication

D.

division

Question

For which operations is the set {–1, 1} closed?

 

Choose all answers that are correct.


  A. 
 
addition
   
    


  

  B. 
 
subtraction
   
    


  

  C. 
 
multiplication
   
    


  

  D. 
 
division

zepdrix · Answer

Hey Cherry :)
Welcome to OpenStudy.

Let's try the first option performed on some of the elements in our set.
Addition:
1+1 = 2
1+(-1) = 0

Hmm we were able to `leave` the set {-1,1} by performing addition on two members of the set. So this set is `open` under addition. Not closed because 2 is not in {-1,1}, neither is 0.