Which one is a irrational number and why ?

Option A, the square root of 40, is an irrational number.

Step-by-step 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!

A. √40

Step-by-step explanation:

√49 = 7

√100 = 10

√9 = 3

but,

√40 = 6.32455532, so this is immperfect square