Answer: Option A, the square root of 40, is an irrational number.
Explanation:
We are given 4 options:
- the sqrt of 40
- the sqrt of 49
- the sqrt of 100
- the sqrt of 9
All but one are perfect squares. Let's find out which one is not a perfect square.
The sqrt of 49 is 7. 7 times 7 is equal to 49.
The sqrt of 100 is 10. 10 times itself is equal to 100.
The sqrt of 9 is 3. 3 times 3 is equal to 9.
What about the square root of 40?
We know it's not a perfect square, and it's somewhere between 6 and 7. So, the hint from the question tells us that imperfect squares are irrational. Then this must be the answer!