## anonymous one year ago Which of the following is a rational number? square root 15 square root 16, square root 21, square root 22 square root 15 square root 16 square root 21 square root 22

1. Michele_Laino

hint: $\Large 16 = {4^2}$ whereas 15, 21, and 22 are not perfect squares

2. Michele_Laino

so we can write: $\Large \sqrt {16} = 4 = \frac{4}{1}$

3. Michele_Laino

for example we can not find a pair of positive integer, say m and n, such that $\Large \sqrt {21} = \frac{m}{n}$ with n different from zero

4. Michele_Laino

integers*

5. anonymous

sorry

6. Michele_Laino

no worries! :) what is the right option?

7. anonymous

8. Michele_Laino

better is square root of 16

9. anonymous

yes square root 16 is the right answer (:

10. Michele_Laino

correct!

11. anonymous

i knew it was the right answer cause thats what i had

12. Michele_Laino

ok!