Tính:
a, I = \(\frac{1}{1.2}\)+ \(\frac{1}{2.3}\)+\(\frac{1}{3.4}\)+ ...+ \(\frac{1}{2009.2010}\)
b, K = \(\frac{4}{2.4}\)+ \(\frac{4}{4.6}\)+ \(\frac{4}{6.8}\)+...+ \(\frac{4}{2008.2010}\)
c, F = \(\frac{1}{18}\)+ \(\frac{1}{54}\)+ \(\frac{1}{108}\)+...+ \(\frac{1}{990}\)