5sqrt(2) -1=(5sqrt(2)-1)*(5sqrt(2)+1)/(5sqrt(2)+1)= =((5sqrt(2))^2-1)/(5sqrt(2)+1)=(50-1)/(5sqrt(2)+1) [b]sqrt(5sqrt(2)-1)=7/sqrt(5sqrt(2)+1) [/b] sqrt(2)+1=(sqrt(2)+1)*(sqrt(2)-1)/(sqrt(2)-1)=(sqrt(2))^2-1^2)/(sqrt(2)-1)= =1/(sqrt(2)-1) sqrt(sqrt(2)+1)=1/sqrt(sqrt(2)-1)