a)
\frac{2}{3+\sqrt5}=\frac{2*(3-\sqrt5)}{(3+\sqrt5)*(3-\sqrt5)}=\frac{2(3-\sqrt5)}{3^2-(\sqrt5)^2}=\frac{2(3-\sqrt5)}{9-5}=
=\frac{\not2^1(3-\sqrt5)}{\not4^2}=\frac{3-\sqrt5}{2}
b)
\frac{6}{2-\sqrt3}=\frac{6*(2+\sqrt3)}{(2-\sqrt3)*(2+\sqrt3)}=\frac{6(2+\sqrt3)}{2^2-(\sqrt3)^2}=\frac{6(2+\sqrt3)}{4-3}=
=\frac{6(2+\sqrt3)}{1}=6(2+\sqrt3)
Zastosowany wzór skróconego mnożenia:
(a-b)(a+b)=a^2-b^2 różnica kwadratów