Question

How do you simplify `(6 + sqrt 5) (6 - sqrt5)`?

Answer 1

`(6+sqrt(5))(6-sqrt(5)) = 31`

Explanation:

`(a+b)(a-b) = (a^2-b^2)`

Replacing `a` with `6`
and `b` with `sqrt(5)`

`(6+sqrt(5))(6-sqrt(5))`

`color(white)("XXX")=(6^2-(sqrt(5))^2)`

`color(white)("XXX")=(36-5)`

`color(white)("XXX")=31`