9.2: Arithmetic Sequences

Arithmetic sequences are when you are constantly adding the same thing to the previous term. 

Example of a arithmetic sequence

2, 4, 6, 8 

The common difference is 2

Common difference formula

When d is the common difference...

d=a2-a1

Explicit formula for arithmetic sequences

an=a+(n-1)d

Example:

Find the arithmetic sequence of 2, 4, 6, 8 

Sum of an arithmetic sequence 

Sn= n/2 (a1+an) 

Sn=sum of the arithmetic sequence

n=total number of terms

a1=first term

an=last term

Recursive formula

Use the recursive formula when you have to find the first n terms of a formula where you add on to the term before. 

Math joke of the day: