Zadanie 5
\frac{4}{\sqrt6}=\frac{4*\sqrt6}{\sqrt6*\sqrt6}=\frac{4\sqrt6}{6}=\frac{2\sqrt6}{3}
Zadanie 6
(x+3)^2=(x-5)(x+5)
x^2+6x+9=x^2-25
x^2+6x-x^2=-25-9
6x=-34
x=-\frac{34}{6}=-\frac{17}{3}
x=-5\frac{2}{3}
Zadanie 7
\frac{7}{\sqrt2-5}=\frac{7(\sqrt2+5)}{(\sqrt2-5)(\sqrt2+5)}=\frac{7(\sqrt2+5)}{(\sqrt2)^2-5^2}=\frac{7(\sqrt2+5)}{2-25}=-\frac{7(\sqrt2+5)}{23}