Yes, the set is closed.
No. A number cannot be closed under addition: only a set can be closed. The set of rational numbers is closed under addition.
Yes, it is.
Yes, it is.
No, it is not. Division by zero (a rational) is not defined.
Yes. In general, the set of rational numbers is closed under addition, subtraction, and multiplication; and the set of rational numbers without zero is closed under division.
Yes, the set is closed.
The set of rational numbers is closed under division, the set of integers is not.
No. A number cannot be closed under addition: only a set can be closed. The set of rational numbers is closed under addition.
The set of rational numbers is closed under all 4 basic operations.
yes
Yes, it is.
Yes, it is.
Yes, it is.
No, it is not. Division by zero (a rational) is not defined.
No. The set of rational numbers is closed under addition (and multiplication).
Subtraction.