Đưa thừa số ra ngoài dấu căn

a) \(\sqrt{52} = \sqrt{4 \cdot 13} = \sqrt{2^2 \cdot 13} = 2\sqrt{13}\) b) \(\sqrt{27a} = \sqrt{9 \cdot 3a} = \sqrt{3^2 \cdot 3a} = 3\sqrt{3a}\) c) \(\sqrt{50\sqrt{2} + 100} = \sqrt{25 \cdot 2\sqrt{2} + 25 \cdot 4} = \sqrt{25(2\sqrt{2} + 4)} = \sqrt{5^2 \cdot (2\sqrt{2} + 4)} = 5\sqrt{2\sqrt{2} + 4}\) d) \(\sqrt{9\sqrt{5} - 18} = \sqrt{9(\sqrt{5} - 2)} = \sqrt{3^2 \cdot (\sqrt{5} - 2)} = 3\sqrt{\sqrt{5} - 2}\)