One thing that I learned this week in Pre Calc 11 is how to find the common difference for a Arithmetic Sequence. The definition of a sequence is an ordered list of numbers. In a arithmetic sequence it starts at a number ( or a) then each term goes up or down by the same amount each time. For instance, 7,10,13,16,… is a arithmetic sequence, because each step adds three, and 18,11,4,-3,… is a arithmetic sequence, because each step subtracts 7. The amount the term goes up or down by is the constant. The constant is also called the common difference (d).

To find the common difference of a sequence we use this equation d =  – 

Below is an example shown of the steps I would take to find the common difference of a arithmetic sequence using the equation above.