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

tkhunny · Answer

Why not test it out?

1 + (-1) = 0 -- So much for addition
Go!

aaalive · Answer

I don't know, thats why I asked

anonymous · Answer

A, C, D... im not sure about d because some of them are undefined

katie_rogers101 · Answer

Division:
\frac{-1}{1}=-1 \&#10;\frac{1}{-1}=-1 \ \frac{-1}{-1}=1 \ \frac{1}{1}=1

katie_rogers101 · Answer

that didn't post our right

tkhunny · Answer

You don't know what?  The definition of "Closed"?  Experiment!  SEE if they are closed.

I tried it under addition and it failed.  You try it under the other operations and see hwt happens.

katie_rogers101 · Answer

If you work through all of the problems you can determine that subtraction is not closed either

katie_rogers101 · Answer

so now you are left with 2 options

tkhunny · Answer

There is nothing undefined in this exercise.  Is the result in the set or not?

anonymous · Answer

nm i was thinking interval notation. the answer is division and multiplication

katie_rogers101 · Answer

actually it is not division and multiplication. It is just division.

tkhunny · Answer

It's also closed under Multiplication.