Question

(5+square root 5)(5-squaure root 5)

Answer 1

Answer:

= (5+√5)(5-√5)

= (a+b)(a-b)=a²-b²

Here, a=5 & b=√5

= (5)²-(√5)²

= 25-5

= 20

_______________.

Answer 2

$(5 + \sqrt{5} )(5 - \sqrt{5} )$

the term is given as (a + b)(a - b)

$(a + b)(a - b) = {a}^{2} - {b}^{2}$

$∴(5 + \sqrt{5} )(5 - \sqrt{5} ) = {(5)}^{2} - { (\sqrt{5}) }^{2}$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 25 - 5$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 20$