Question

Is addition a binary operation on the set {-1,0,1,} ?
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Answer 1

Answer:

Yes

Step-by-step explanation:

-1 + 0 = 0

0+1=0

-1+1=0

Answer 2

Answer:

yes

Step-by-step explanation:

A set X is closed under addition if x+y∈X for any x,y∈X. It is closed under multiplication if x×y∈X for any x,y∈X. Note that x and y may or may not be equal.

The set {−1,0,1} is closed under multiplication but not addition (if we take usual addition and multiplication between real numbers). Simply verify the definitions by taking elements from the set two at a time, possibly the same.