Question

How to simplify the square root of 3 over the square root of 21

Answer 1

3 * 7 = 21, so

$\sqrt{21}=\sqrt{3\cdot7}=\sqrt3\sqrt7$

Then

$\dfrac{\sqrt3}{\sqrt{21}}=\dfrac1{\sqrt7}$

and you can rationalize the denominator to write this as

$\dfrac1{\sqrt7}\cdot\dfrac{\sqrt7}{\sqrt7}=\dfrac{\sqrt7}7$

Answer 2

answer: √3⋅√21 = 3√7