1. Tính: \(\left[\sqrt{12}+3\sqrt{15}-4\sqrt{135}\right]\cdot\sqrt{3}\)
\(\sqrt{252}-\sqrt{700}+\sqrt{1008}-\sqrt{448}\)
\(2\sqrt{40\cdot\sqrt{12}}-2\sqrt{\sqrt{75}}-3\sqrt{5\sqrt{48}}\)
2. Rút gọn biểu thức: \(\frac{\sqrt{6}+\sqrt{4}}{2\sqrt{3}+\sqrt{28}}\)
\(\frac{9\sqrt{5}+3\sqrt{27}}{\sqrt{5}+\sqrt{3}}\)
\(\frac{3\sqrt{8}-2\sqrt{12}+\sqrt{20}}{3\sqrt{18}-2\sqrt{27}+\sqrt{45}}\)