применяем формулу (a^2-2ab+b^2=(a+b)^2
=8-2*(2sqrt(2))*sqrt(7) + 7=
=(2sqrt(2)-sqrt(7))^2
тогда
sqrt(15-4sqrt(14))=|2sqrt(2)-sqrt(7)|= [b]sqrt(7)-2sqrt(2)[/b]
Аналогично
15+4sqrt(14)=15+2*2*sqrt(2)*sqrt(7)=
применяем формулу(a^2+2ab+b^2=(a+b)^2
=8+2*(2sqrt(2))*sqrt(7) + 7=
=(2sqrt(2)-sqrt(7))^2
sqrt(15+4sqrt(14))=|2sqrt(2)+sqrt(7)|= [b]2sqrt(2)+sqrt(7)[/b]
а=sqrt(15-4sqrt(14))-sqrt(15+4sqrt(14))=
=sqrt(7)-2sqrt(2)-(2sqrt(2)+sqrt(7))= [b] - 4sqrt(2)[/b]