**Progressions and Series**

In this chapter we will study Sequence which is a succession of numbers formed according to some definite rule. For example 1, 3, 5, 7,9 ……. is a sequence, here each term of the sequence can be obtained by adding 2 to the preceding term.

There are two types of sequence .i.e Finite sequence and Infinite sequence. A sequence is said to be a finite or infinite according as it has finite or infinite number of terms.

If {fn} be a sequence then an expression of the form f1 + f2 + …… + fn is called Series. In other word a series is the sum of the terms of the sequence.

If the terms of a sequence are written under specific condition then the sequence is called progression. There are three types of progressions.

**i) Arithmetic Progression **

**ii) Geometric Progression**

iii) Harmonic Progression

Progressions and Series is important from the perspective of scoring high in IIT JEE as it fetches 1-2 questions in most of the engineering examination there are few fixed pattern on which a number Multiple Choice Questions are framed on this topic. You are expected to do all the questions based on this to remain competitive in IIT JEE examination. It is very important to master these concepts at early stage as this forms the basis of your preparation for IIT JEE, AIEEE, DCE, EAMCET and other engineering entrance examinations.