Question

which of the following sets is closed under subtraction? irrational numbers natural numbers whole numbers integers

Explanation:

A set is closed under subtraction if subtracting any two elements of the set results in another element of the set.

1. Irrational numbers: For example, $\sqrt{2} - \sqrt{2} = 0$, which is rational, so they are not closed.
2. Natural numbers: For example, $3 - 5 = -2$, which is not a natural number, so they are not closed.
3. Whole numbers: For example, $2 - 4 = -2$, which is not a whole number, so they are not closed.
4. Integers: Subtracting any two integers ($a - b$ where $a,b \in \mathbb{Z}$) always gives an integer, so they are closed.

Answer:

integers