Question

EVALUATE--
(2-root 5) (2+root 5)

GUYS ANSWER fast I'LL MARK IT BRAINLIST!!

Answer 1

Answer:

-1

Step-by-step explanation:

$(2 - \sqrt{5} )(2 + \sqrt{5} )\\ \\ \\ as \\ {a}^{2} - {b}^{2} \: =( a + b)(a - b)$

4-5= -1

Answer 2

$</p><p></p><p>\underline{\color{cyan}Given\;Question\;Is}\\\\</p><p></p><p>{\color{red} (2-\sqrt{5})*(2+\sqrt{5})} \\\\</p><p></p><p>\underline{\underline{\color{green}Answer}} \\\\</p><p></p><p>{\color{blue}(2-\sqrt{5})*(2+\sqrt{5})} \\\\</p><p></p><p>\implies{(2^2 -(\sqrt{5})^2)} \\ \\ </p><p></p><p>\boxed{\color{red}Bcoz\;\; (a-b)*(a+b)=(a^2-b^2)} \\\\</p><p></p><p>\implies{(4-5)} \\ \\</p><p></p><p>=-1 \\ \\</p><p></p><p>\therefore\;\; {\color{blue}(2-\sqrt{5})*(2+\sqrt{5})=-1} \\\\</p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p>$