Question

How do you simplify `21/sqrt7`?

Answer 1

`=color(blue)(3sqrt7`

Explanation:

`21/sqrt7`

Rationalising the denominator:

`21/sqrt7= (21 xx color(blue)(sqrt7))/(sqrt7 xx color(blue)(sqrt7`

`=(21sqrt7)/7`

`=(cancel21sqrt7)/cancel7`

`=color(blue)(3sqrt7`