Question

Which of the following sets is written in the set builder form?

• A. $Q=\left\{1,2,3,4,5\right\}$
• B. $A=\left\{x:xisacountingnumbergreaterthan9\right\}$
• C. $P=\left\{Thelastfourmonthsofayear\right\}$
• D. None of these

Answer 1

The correct option is B

$A=\left\{x:xisacountingnumbergreaterthan9\right\}$

Explanation for the correct option:

Option b: $A=\left\{x:xisacountingnumbergreaterthan9\right\}$

In set builder form, we describe the properties satisfied by the elements enclosing it in curly brackets.

Hence the given option is in set builder form as it describes the properties of the elements as counting numbers greater than $9$.

Explanation for the incorrect options:

Option a: $Q=\left\{1,2,3,4,5\right\}$

Since all the elements are directly given, it is called as the roster form of sets.

Option c: $P=\left\{Thelastfourmonthsofayear\right\}$

The given option represents the descriptive form. It describes the elements of the set.

Hence, it is not in set builder form.