Question

(2√10-√2)²
преобразовать 

Answer 1

$(2sqrt{10}-sqrt{2})^2=(2sqrt{5*2}-sqrt{2}*1)^2=\\(sqrt{2}*(2sqrt{5}-1))^2=\\(sqrt{2})^2*(2sqrt{5}-1)^2=2*((2sqrt{5})^2-2*2sqrt{5}*1+1^2)=\\2*(4*5-4sqrt{5}+1)=2*(20-4sqrt{5}+1)=\\2*(21-4sqrt{5})=42-8sqrt{5}$