Final answer:
The set 7, 14, 21 is expressed in set-builder notation as x , where N is the set of natural numbers.
Step-by-step explanation:
The set containing the numbers 7, 14, 21 can be written in set-builder notation which provides a rule or property that all elements of the set share. To express the given set in set-builder notation, we look for a common characteristic among the numbers.
Here, each number is a multiple of 7. Thus, we can define the set as x , where N represents the set of natural numbers.Set-builder notation is a way to describe a set of elements using a rule or condition.
Set-builder notation is a mathematical notation used to describe sets in a concise and systematic way. It provides a formal method of defining sets by specifying the properties or conditions that the elements in the set must satisfy. This notation is particularly useful in defining sets with infinite elements or complex characteristics.