Chapter 10 - Radical Expressions and Equations - 10-3 Operations with Radial Expressions - Practice and Problem-Solving Exercises - Page 616: 28

$-\sqrt{6}$

Multiply using $FOIL$. $(\sqrt{6}+\sqrt{3})(\sqrt{2}-2)=\sqrt{6}\cdot \sqrt{2}-2\sqrt{6}+\sqrt{3}\cdot \sqrt{2}-2\sqrt{3}=\sqrt{12}-2\sqrt{6}+\sqrt{6}-2\sqrt{3}=\sqrt{12}-\sqrt{6}-2\sqrt{3}=2\sqrt{3}-\sqrt{6}-2\sqrt{3}=-\sqrt{6}$