[tex] \text{Conjugatul numarului }\sqrt{6}+ \sqrt{3},\; este \; \sqrt{6}- \sqrt{3} \\ \\ \frac{4}{ \sqrt{6}+ \sqrt{3}}= \frac{4( \sqrt{6}- \sqrt{3})}{(\sqrt{6}+ \sqrt{3})( \sqrt{6}- \sqrt{3})}= \frac{4( \sqrt{6}- \sqrt{3})}{ (\sqrt{6})^{2}- (\sqrt{3})^{2}}=\frac{4( \sqrt{6}- \sqrt{3})}{ 6- 3}=\boxed{\frac{4( \sqrt{6}- \sqrt{3})}{3}}[/tex]
