Question

(5+√5) (5-√5)
Simplify

Answer 1

$(5 + \sqrt{5} )(5 - \sqrt{5} ) \\ using \: identity \\ (x + y)(x - y) = {x}^{2} - {y}^{2} \\ (5 + \sqrt{5} )(5 - \sqrt{5} ) \\ = {5}^{2} - {( \sqrt{5)} }^{2} \\ = 25 - 5 \\ = 20 \: \: \: \: \: \: \: \: \: \: \: \: \: ans$