Question

(5+√5)(5-√5)=20
answer​

Answer 1

Step-by-step explanation:

LHS

$(5 + \sqrt{5} )(5 - \sqrt{5)} \\ using \: identity \: (a - b)(a + b) = a {}^{2} - b {}^{2} \\ = 5 {}^{2} - ( \sqrt{5)} {}^{2} \\ = 25 - 5 \\ = 20 = rhs$