Câu hỏi 13$\frac{2\sqrt6}{\sqrt2+\sqrt3+\sqrt5}$ bằng$\sqrt2+\sqrt3-\sqrt5$$4-\sqrt2-\sqrt3$$\sqrt2+\sqrt3+\sqrt6-5$$\frac12(\sqrt2+\sqrt5-\sqrt3)$$\frac13(\sqrt3+\sqrt5-\sqrt2)$