Giải thích các bước giải:
c.$C=\dfrac{2(\sqrt{2}-\sqrt{6})}{3(\sqrt{2-\sqrt{3}})}$
$\to C=\dfrac{2.\sqrt{2}(\sqrt{2}-\sqrt{6})}{3\sqrt{2-\sqrt{3}}.\sqrt{2}}$
$\to C=\dfrac{2.2(1-\sqrt{3})}{3\sqrt{4-2\sqrt{3}}}$
$\to C=\dfrac{4(1-\sqrt{3})}{3\sqrt{3-2\sqrt{3}+1}}$
$\to C=\dfrac{4(1-\sqrt{3})}{3\sqrt{(\sqrt{3}-1)^2}}$
$\to C=\dfrac{4(1-\sqrt{3})}{3(\sqrt{3}-1)}$
$\to C=-\dfrac{4}{3}$
