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How do you simplify $(6 + sqrt 5) (6 - sqrt5)$ ?

1 Answer

Oct 15, 2015

$(6+sqrt(5))(6-sqrt(5)) = 31$

Explanation:

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

Replacing $a$ with $6$
and $b$ with $sqrt(5)$

$(6+sqrt(5))(6-sqrt(5))$

$color(white)("XXX")=(6^2-(sqrt(5))^2)$

$color(white)("XXX")=(36-5)$

$color(white)("XXX")=31$

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