No, the set of odd numbers is not closed under subtraction. For example, if you subtract one odd number from another odd number, such as 5 - 3, the result is 2, which is an even number and not part of the set of odd numbers. Therefore, the subtraction of odd numbers can yield results that fall outside the set.
Yes. The entire set of natural numbers is closed under addition (but not subtraction). So are the even numbers (but not the odd numbers), the multiples of 3, of 4, etc.
It is not closed under taking square (or other even) roots.
Yesss.
Yes, because suppose that 'a' and 'b' are both arbitrary integers. Then (a-b) or (b-a) will then provide you with another integer. Suppose that the integer you are given from (a-b) is not unique. Then we have: (a-b)=c and (a-b)=c' Then, trivially, since (a-b)=(a-b), we have c=c'. Thus it is closed under subtraction.
No, the set of odd numbers is not closed under subtraction. For example, if you subtract one odd number from another odd number, such as 5 - 3, the result is 2, which is an even number and not part of the set of odd numbers. Therefore, the subtraction of odd numbers can yield results that fall outside the set.
Yes. The entire set of natural numbers is closed under addition (but not subtraction). So are the even numbers (but not the odd numbers), the multiples of 3, of 4, etc.
The set of even numbers is closed under addition, the set of odd numbers is not.
Subtraction: Yes. Division: No. 2/4 = is not an integer, let alone an even integer.
The numbers are not closed under addition because whole numbers, even integers, and natural numbers are closed.
It is not closed under taking square (or other even) roots.
Yesss.
Yes, it is closed. This means that if you multiply two even number, you again get a number within the set of even numbers.
Yes, when you add any two even numbers, the result is always an even number.
No. 2/4 is not an even number.
Yes, because suppose that 'a' and 'b' are both arbitrary integers. Then (a-b) or (b-a) will then provide you with another integer. Suppose that the integer you are given from (a-b) is not unique. Then we have: (a-b)=c and (a-b)=c' Then, trivially, since (a-b)=(a-b), we have c=c'. Thus it is closed under subtraction.
Unfortunately, the term "whole numbers" is somewhat ambiguous - it means different things to different people. If you mean "integers", yes, it is closed. If you mean "positive integers" or "non-negative integers", no, it isn't.