1. TÍNH
a) \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+.....+\frac{1}{10100}\)
b) \(\frac{1}{2.4}+\frac{1}{4.6}+\frac{1}{6.8}+...+\frac{1}{66.68}\)
c) \(\frac{3}{10}+\frac{3}{40}+\frac{3}{88}+...+\frac{3}{340}\)
d) \(\frac{6}{15}+\frac{6}{35}+\frac{6}{63}+\frac{6}{99}\)