Question

(5+underroot5)(5-underroot5

Answer 1

$(5 + \sqrt{5} )(5 - \sqrt{5} ) \\ {(5)}^{2} - {( \sqrt{5} )}^{2} \\ 25 - 5 \\ => 20$

Answer 2

Step-by-step explanation:

Given that( 5+√5)(5-√5).

This is in the form of (a+b)(a-b).

we know that (a+b)(a-b)=a^2-b^2

here, a =5 and b=√5

now, (5+√5)(5+√5)=5^2-(√5)^2

=>25-5=20

Therefore,(5+√5)(5-√5)=20