Expert: Ahmed Salami - 8/13/2010

Question
if a1 =4 and d=2 what are the first four terms of the arithmetic sequence? and what is 10!/5!.

Answer
Hi Mark,
1. If a_1 = 4 and d = 2, then
a_2 = a_1 + d = 4 + 2 = 6
a_3 = a_2 + d = 6 + 2 = 8
a_4 = a_3 + d = 8 + 2 = 10
Generally, the nth term of the arithmetic sequence would be
a_n = a_1 + (n-1)d

2. 10!/5! = (10 x 9 x 8 x 7 x 6 x 5!)/5!
         = 10 x 9 x 8 x 7 x 6
         = 30240

Regards