Question

The set {-1, 0, 1} is not closed under which operation?

Answer 1

Hello,

if find the square root of a real is an operation then
√(-1)∉{-1,0,1}.

Answer 2

The set {-1, 0, 1} is NOT closed under subtraction.
-1- (0) = -1
But,
 -1 - (1) = -2
Hence,The result -2 is not in the set.
I hope it helped.