General Forms of a Sequence

• Sequence: a list of numbers
• Finite Sequence: a sequence that ends

              Example : 1,3,9,12 

• Infinite Sequence: a sequence that keeps going 

             Example: 1,3,9,12,15,18...

Types of Sequences 

• Arithmetic Sequence: have a common difference and you find it by subtracting the last number from the next and so on. 

                       Example:  1,4,7,10,13 

                       13-10 =3 

                       10-7=3

                        7-4=3

                        4-1=3                      

                                  So the common difference is 3 which is represented as d=3 

The formula that represents arithmetic sequences is:

             

• Geometric Sequences: have a common ration and you can find it by dividing the last number by the next number. 

                              Example : 4,24,144,864....

                          864/144=6

                          144/24=6

                           24/4=6

                                                  So the common ration is 6 represented as r=6

The formula that represents geometric sequences :

To find a specific term in a sequence you  just plug that number into the A_n