Question

Expand:

`(2 + sqrt(5))^2`

Answer 1

We have, `(2 + sqrt(5))^2`

= `2^2 + (sqrt(5))^2 + 2 xx 2 xx sqrt(5)`  ...[Use (a + b)² = a² + b² + 2ab]

= `4 + 5 + 4sqrt(5)`

= `9 + 4sqrt(5)`

Therefore, the required is `9 + 4sqrt(5)`.