Answer:
To determine which of these numbers is not a perfect square, we need to understand what a perfect square is.
A perfect square is a number that can be expressed as the square of an integer. In other words, it is the result of multiplying an integer by itself.
Let's analyze each number:
1. 25: This is a perfect square because it can be expressed as 5 * 5 or 5^2.
2. 3: This is not a perfect square because it cannot be expressed as the square of an integer. There is no integer that, when multiplied by itself, gives us 3.
3. 9: This is a perfect square because it can be expressed as 3 * 3 or 3^2.
4. 36: This is a perfect square because it can be expressed as 6 * 6 or 6^2.
Therefore, the number 3 is not a perfect square. It is the only number in the given list that cannot be expressed as the square of an integer.