Yes.
s
In the first stage, the set of all integers needs an extension - to the set of rational numbers - to get closure for division (which is the inverse operation to multiplication).
All numbers - integers as well as non-integers - are combined using different mathematical operations. Some operators are binary: that is, they combine two numbers to produce a third; some are ternary (combine 3 to produce a fourth) and so on.The set of integers is closed under some operations: common examples are addition, subtraction, multiplication, exponentiation. But not all operators are: division, for example.
I am not at all sure that there are any rules that apply to integers in isolation. Any rules that exist are in the context of binary operations like addition or multiplication of integers.
Yes.
no
s
The set of positive integers does not contain the additive inverses of all but the identity. It is, therefore, not a group.
Yes, it is.
To be a group, the set of integers with multiplication has to satisfy certain axioms: - Associativity: for all integers x,y and z: x(yz) = (xy)z - Identity element: there exists some integer e such that for all integers x: ex=xe=x - Inverse elements: for every integer x, there exists an integer y such that xy=yx=e, where e is the identity element The associativity is satisfied and 1 is clearly the identity element, however no integer other than 1 has an inverse as in the integers xy = 1 implies x=y=1
Any set where the result of the multiplication of any two members of the set is also a member of the set. Well known examples are: the natural numbers (ℕ), the integers (ℤ), the rational numbers (ℚ), the real numbers (ℝ) and the complex numbers (ℂ) - all closed under multiplication.
In the first stage, the set of all integers needs an extension - to the set of rational numbers - to get closure for division (which is the inverse operation to multiplication).
In the first stage, the set of all integers needs an extension - to the set of rational numbers - to get closure for division (which is the inverse operation to multiplication).
All numbers - integers as well as non-integers - are combined using different mathematical operations. Some operators are binary: that is, they combine two numbers to produce a third; some are ternary (combine 3 to produce a fourth) and so on.The set of integers is closed under some operations: common examples are addition, subtraction, multiplication, exponentiation. But not all operators are: division, for example.
I am not at all sure that there are any rules that apply to integers in isolation. Any rules that exist are in the context of binary operations like addition or multiplication of integers.
Assuming that the question is in the context of the operation "addition", The set of odd numbers is not closed under addition. That is to say, if x and y are members of the set (x and y are odd) then x+y not odd and so not a member of the set. There is no identity element in the group such that x+i = i+x = x for all x in the group. The identity element under addition of integers is zero which is not a member of the set of odd numbers.