Let's classify each of the given numbers:
-
\( \sqrt{47} \): This number is an irrational number because it cannot be expressed as a fraction of two integers.
-
0.121212...: This number is a repeating decimal, which can be expressed as a fraction. Therefore, it belongs to the set of rational numbers.
-
0: This number is an integer (it can also be classified as a whole number and a rational number, but integer is the most specific set for it).
-
\( \sqrt{144} \): This number equals 12, which is a whole number (and also a natural number and an integer, but whole number is the most specific classification).
-
-9: This number is an integer (it cannot be classified as a natural number or a whole number, but it is a member of the integer set).
So the specific sets are:
- \( \sqrt{47} \): Irrational number
- 0.121212...: Rational numbers
- 0: Integer
- \( \sqrt{144} \): Whole number
- -9: Integer