Question

Simplify: (2+√5) (2-√5).​

Answer 1

Answer:

Step-by-step explanation:

use identity [ a+b] [a-b] = a square - b square

[ 2+ root 5] [ 2 - root 5] =  2 square - root   5 square

                                       = 4- 5

                                      = -1

Answer 2

Answer:

-1

Step-by-step explanation:

(2+√5) (2-√5)

in the form of (a+b)(a-b)=a²-b²

(2+√5) (2-√5)=(2)²-(√5)²

=4-5=-1