rút gọn
A=\(\frac{\sqrt{3}-\sqrt{6}}{1-\sqrt{2}}-\frac{2+\sqrt{8}}{1+\sqrt{2}}\)
B=\(\left(1-\sqrt{5}\right)\left(\frac{\sqrt{5}+5}{2\sqrt{5}}\right)\)
C=\(\sqrt{4+\sqrt{7}}\)+\(\sqrt{4-\sqrt{7}}\)
D=\(2\sqrt{8}-4\sqrt{\left(\sqrt{2}+1\right)^2}\)
giup minh nhe các bạn