Answer
$\dfrac{2}{5-\sqrt{21}}$
Work Step by Step
Simplify. $ \dfrac{\sqrt 7+ \sqrt 3}{\sqrt 7 -\sqrt 3}$
Now, $ \dfrac{\sqrt 7+ \sqrt 3}{\sqrt 7 -\sqrt 3}= \dfrac{\sqrt 7+ \sqrt 3}{\sqrt 7 -\sqrt 3} \times \dfrac{\sqrt 7- \sqrt 3}{\sqrt 7 -\sqrt 3}$
or, $=\dfrac{(\sqrt 7)^2-(\sqrt 3)^2}{7+3-2\sqrt 7 \sqrt 3}$
$\implies \dfrac{2}{5-\sqrt{21}}$
