Question

How do you simplify `(6+sqrt 7)(6-sqrt 7)`?

Answer 1

`=color(blue)(29`

Explanation:

`(6+sqrt7)(6-sqrt7)`

The above expression is of the form
`color(blue)((a+b)(a-b) = a^2 - b^2`

`color(blue)(a=6, b=sqrt7`

So,
`(6+sqrt7)(6-sqrt7) = color(blue)(6^2 - (sqrt7)^2`

`=36-7`

`=29`