Page 219 -

212 Chapter Three

1! 1

2! 2

3! 6

4! 24

5! 120

6! 720

7! 5,040

8! 40,320

9! 362,880

10! 3,628,800

11! 39,916,800

12! 479,001,600

Arithmetic series

An arithmetic series is a serieð A such that:

f(a n 1 ) a d
n

A a (a d) (a 2d) (a 3d) ...
1
1
1
1
where d is a constant called the difference. For example, if a
1
5 and d 2, then:
A 5 7 9 11 13 ...

Geometric series
A geometric series is a serieð G such that:

f(a ) a /r
n 1 n

2
3
G a (a /r) (a /r ) (a /r ) ...
1
1
1
1