3) $\sqrt{4-2\sqrt{3}}$
$=\sqrt{3-2\sqrt{3}+1}$
$=\sqrt{(\sqrt{3}-1)^2}$
$=\sqrt{3}-1$
4) $\sqrt{11+6\sqrt{2}}$
$=\sqrt{9+6\sqrt{2}+2}$
$=\sqrt{(3+\sqrt{2})^2}$
$=3+\sqrt{2}$
5) $\sqrt{27-10\sqrt{2}}$
$=\sqrt{25-10\sqrt{2}+2}$
$=\sqrt{(5-\sqrt{2})^2}$
$=5-\sqrt{2}$