Yes.
Yes they are closed under multiplication, addition, and subtraction.
Yes, polynomials are a closed set under addition. This means that if you take any two polynomials and add them together, the result will also be a polynomial. The sum of two polynomials retains the structure of a polynomial, as it still consists of terms with non-negative integer exponents and real (or complex) coefficients.
No. A number cannot be closed under addition: only a set can be closed. The set of rational numbers is closed under addition.
Yes, polynomials are closed under the operations of addition, subtraction, and multiplication. This means that when you add, subtract, or multiply two polynomials, the result is always another polynomial. For example, if ( p(x) ) and ( q(x) ) are polynomials, then ( p(x) + q(x) ), ( p(x) - q(x) ), and ( p(x) \cdot q(x) ) are all polynomials as well. However, polynomials are not closed under division, as dividing one polynomial by another can result in a non-polynomial expression.
Quite simply, they are closed under addition. No "when".
Yes they are closed under multiplication, addition, and subtraction.
Yes, because there is no way of multiplying two polynomials to get something that isn't a polynomial.
It means that you can do any of those operations, and again get a number from the set - in this case, a polynomial. Note that if you divide a polynomial by another polynomial, you will NOT always get a polynomial, so the set of polynomials is not closed under division.
No. A number cannot be closed under addition: only a set can be closed. The set of rational numbers is closed under addition.
Quite simply, they are closed under addition. No "when".
The set of even numbers is closed under addition, the set of odd numbers is not.
Yes, the set of non-deterministic polynomial time (NP) problems is closed under the operation of union.
The numbers are not closed under addition because whole numbers, even integers, and natural numbers are closed.
+,-,X only
yes because real numbers are any number ever made and they can be closed under addition
That is correct, the set is not closed.
Yes. The set of real numbers is closed under addition, subtraction, multiplication. The set of real numbers without zero is closed under division.