1. Finite Differences

2. Finite Differences
If the sequence does not fall into an arithmetic or Geometric progression you can use Finite Differences to find the Explicit Formula.
Stop!
Equation is 2nd degree.

3. Now we will create 3 equations:
Plug 1, 2 and 3 in for x (1, 2, 3 stands for the term number)
Now solve 3 equations with 3 variables.

4. Example Find the function that gives the following sequence.
3, 11, 31, 69, 131….

5. Sigma Notation
Sigma Notation is a notation used to abbreviate long summations of a given expression .
Where n is the upper boundary and m is the lower boundary.

6. Sum of an Arithmetic Progression:

7. Sum of a Geometric Progression

8. Example
Find the sum of the following: