What Is a Sequence?

A sequence is an ordered list of numbers that follow a specific pattern.
Each number in a sequence is called a term.

Example:
2, 4, 6, 8, 10, …

• The first term is usually called a₁

• The position of a term is shown with n

• The value of a term is written as aₙ

Arithmetic Sequence

Explanation

An arithmetic sequence is a sequence where you add or subtract the same number each time to get the next term.

That constant number is called the common difference (d).

Examples:

• 3, 7, 11, 15, … (add 4 each time)

• 20, 15, 10, 5, … (subtract 5 each time)

How to check:
Subtract one term from the next:
If the result is always the same → arithmetic sequence