\[\frac{1}{\sqrt{4 - 2\sqrt{3}}} - \frac{1}{\sqrt{4 + 2\sqrt{3}}} =\]
\[= \frac{1}{\sqrt{3 - 2\sqrt{3} + 1}} - \frac{1}{\sqrt{3 + 2\sqrt{3} + 1}} =\]
\[= \frac{1}{\sqrt{\left( \sqrt{3} - 1 \right)^{2}}} - \frac{1}{\sqrt{\left( \sqrt{3} + 1 \right)^{2}}} =\]
\[= \frac{1}{\left| \sqrt{3} - 1 \right|} - \frac{1}{\left| \sqrt{3} + 1 \right|} =\]
\[= \frac{1}{\sqrt{3} - 1} - \frac{1}{\sqrt{3} + 1} =\]
\[= \frac{\sqrt{3} + 1 - \left( \sqrt{3} - 1 \right)}{\left( \sqrt{3} - 1 \right)\left( \sqrt{3} + 1 \right)} =\]
\[1 - рациональное \Longrightarrow ч.т.д.\]