# Sequences and Series

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More Lessons for Algebra II
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A series of free, online Intermediate Algebra Lessons or Algebra II lessons.

Videos, worksheets, and activities to help Algebra students.

In this lesson, we will learn

- how to define sequences
- how to define a series
- how to write a series in summation notation

### Introduction to Sequences

Lists of numbers, both finite and infinite, that follow certain rules are called sequences. This introduction to sequences covers the definition of a sequence and how to identify a rule. There are specific sequences that have their own formulas and methods for finding the value of terms, such as arithmetic and geometric sequences. Series are an important concept that come from sequences.

This video introduces sequences.

How to define a sequence.

### Series and Summation Notation

An important concept that comes from sequences is that of series and summation. Series and summation describes the addition of terms of a sequence. There are different types of series, including arithmetic and geometric series. Series and summation follows its own set of notation that is important to memorize in order to understand homework problems.

How to define a series.

In this video we look at several examples of how to write series in summation notation.

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