1. Tính
a. S = \(\dfrac{1}{1.4}\)+\(\dfrac{1}{4.7}\)+\(\dfrac{1}{7.10}\)+.......+\(\dfrac{1}{2002.2005}\)
b. P = \(\dfrac{3}{1.6}\)+\(\dfrac{3}{6.11}\)+\(\dfrac{3}{11.16}\)+.......+\(\dfrac{3}{96.101}\)
c. Q = \(\dfrac{1}{1.2.3}\)+\(\dfrac{1}{2.3.4}\)+\(\dfrac{1}{3.4.5}\)+.......+\(\dfrac{1}{98.99.100}\)
Help me!