Zadanie 1
\frac{\sqrt2-1}{2\sqrt2+1}=\frac{(\sqrt2-1)(2\sqrt2-1)}{(2\sqrt2+1)(2\sqrt2-1)}=\frac{2*2-\sqrt2-2\sqrt2+1}{(2\sqrt2)^2-1}=\frac{5-3\sqrt2}{4*2-1}=\frac{5-3\sqrt2}{7}
Zadanie 2
\frac{2-a^2}{\sqrt2+a}=\frac{2-(\sqrt8)^2}{\sqrt2-\sqrt8}=\frac{2-8}{\sqrt2-2\sqrt2}=\frac{-6}{-\sqrt2}=\frac{6}{\sqrt2}=
\frac{6\sqrt2}{\sqrt2*\sqrt2}=\frac{6\sqrt2}{2}=3\sqrt2