Question

Which of the following is a rational number: √32 √81 √90 or √125

Answer 1

To determine which of the given square roots is a rational number, we will find the square roots:

1. **√32**:
- The square root of 32 is √(16 × 2) = √16 * √2 = 4√2, which is an irrational number.

2. **√81**:
- The square root of 81 is 9, which is a rational number.

3. **√90**:
- The square root of 90 is √(9 × 10) = √9 * √10 = 3√10, which is an irrational number.

4. **√125**:
- The square root of 125 is √(25 × 5) = √25 * √5 = 5√5, which is an irrational number.

Therefore, the only rational number among the given options is **√81** (which equals 9).