Question

(Корень 5 - 1)(корень 5 - 1)= корень 25 - 1

Answer 1

$(sqrt{5}-1)(sqrt{5}-1)+(sqrt{5}-1)(sqrt{5}+1)=\ =(sqrt{5}-1+sqrt{5}+1)(sqrt{5}-1)=2sqrt{5}(sqrt{5}-1)=\ =10-2sqrt{5}$