Maths Class 11 Chapter 9. Sequences and Series | Page 2

Sequence & Series
A sequence is an ordered collection of objects in which repetitions are allowed . E . g .: 1,1,2,2,2,3,3,4,6,7,8,8,9 ,
Sequences , following specific patterns are called progressions . E . g . If you put 10Rs in piggy bank daily then the amount in money in you piggy bank on next few days will be 10,20,30,40,50 ….. etc .
There is a pattern in this sequence , the difference between any two consecutive numbers is 10 , and thus this sequence is Progression . This type of progression is called Arithmetic Progression .
If you deposit Rs 500 in a bank & bank agrees to double your money every year . Then amount of money in your account over next few years will be 500 , 1000 , 2000 , 4000 , 8000 etc
There is a pattern in this sequence too , here if you divide any two consecutive numbers you will get same value . 1000 / 500 = 2000 / 1000 = 2 & thus this sequence is also Progression . This type of progression is called Geometric Progression
A series is the sum of the terms of a sequence . E . g . for a sequence 1,2,3,3,4 , Series is 1 + 2 + 3 + 3 + 4 .