tính
a/ (\(\sqrt{2006}\)- \(\sqrt{2005}\)).(\(\sqrt{2006}\)+ \(\sqrt{2005}\))
b/ (\(\frac{1}{7-4\sqrt{3}}\)+ \(\frac{2}{7+4\sqrt{3}}\)).(21+4\(\sqrt{3}\))
c/ \(3\sqrt{\frac{9}{8}}\)- \(\sqrt{\frac{49}{2}}\)+ \(\sqrt{\frac{25}{18}}\)
d/ ( \(5\sqrt{28}-2\sqrt{63}+3\sqrt{112}\)) : \(\sqrt{7}\)
e/ \(\left(\sqrt{5}+\sqrt{3}\right)\sqrt{8-2\sqrt{15}}\)
f/ (\(\frac{4\sqrt{21}-4\sqrt{15}-\sqrt{14}+\sqrt{10}}{4\sqrt{6}-2+4\sqrt{15}-\sqrt{10}}\)