# Sequence and Series Class 11 Mathematics Solutions | Exercise - 4.2

## Chapter - 4

__Sequence and Series__

In sequence and series chapter of Class 11, we are going to learn about arithmetic progression, geometric progressions and harmonic progression. In previous exercise i.e exercise - 4.1, we have already learned about the geometric progression, harmonic progression and arithmetic progression.

So in this exercise i.e exercise - 4.2, we are going to learn about the ways of finding sum of infinite geometric series. We are also going to have a look at the solution part of this chapter exercise but before moving forward let's have a little concept about the subtopics involved in this exercise.

__Introduction__

__Introduction__

Class 11 Mathematics fourth chapter named 'The Sequence and Series' is the study of patterns found in sequences and series of numbers. We already have learned about sequence and series in grade 9 and 10 but this chapter was included in grade 11 also inorder to introduce the student the concept of mathematical sequences and series, and how to work with them. It also covers topics such as arithmetic progress, geometric progressions, harmonic progression, infinite series, and the summation of finite and infinite series.

The main motive of this chapter is to equip the student with the knowledge and skills to identify, analyse and solve problems involving sequences and series. By the end of the chapter, the student should be able to determine the sum of a given infinite as well as finite geometric sequence, find the nth term of a sequence, and be able to find common ratio of geometric sequence. Students should also be able to use the properties of arithmetic progression and geometric progressions to solve the given equations.

### Geometric Sequences

A geometric sequence is a sequence of numbers in which the ratio of any term to its preceding term is always the same The geometric sequence is also known as the geometric progression. Geometric sequence and geometric progression are written as G.S., and G.P respectively. Examples of such sequences are;

(a) 1,2,4,8, 16,.....

(b) 3,-9,27,-81,.......

### Sum of Infinite Geometric Series

As I already mentioned, in this exercise we are going to learn, how to find sum of infinite geometric series. While finding the sum of infinite geometric series we are going to use a formula which is, **S = a/1 - r** , where a = first term and r = common ratio of the given series.

### Exercise - 4.2

This PDF contains only the solution of exercises - 4.2 of class 11 Sequence and Series chapter. If you are searching for other exercises then you can find them above. You just have to click on the respective buttons to view the required exercise solutions.

**Note**:

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## Is Class 11 Mathematics Guide Helpful For Student ?

This Notes is intended to help students who struggle with math problems. Student should not completely depend on this Notes for all exercises. If you rely on this Note and simply copy it as is, it may affect your study. Student should also use their own willpower and try to solve problems themselves.

You may use this mathematics guide PDF as a reference. Check all the answers before copying because all the answers may not be correct. There may be some minor mistakes in the Notes.

## How to secure good marks in Mathematics Exam?

In case you didn't know, I also am a student. Being a student isn't an easy task as you have to study many different subjects at the same time. From my perspective, most students are weak in mathematics. You can take me as an example as I am also weak in mathematics, and I face some difficulties when I try to answer mathematics questions.

To achieve good marks in mathematics, you must practice them every day. Once each week, you should review all the exercises that were taught in class. When you are solving math problems, start with easy questions that you already know. Doing so you won't get bored instead you'll start enjoying it.

I think all of us can agree that mathematics is more than just practising. It is important that you understand the basic concepts of the problem, especially in grade 11. Once you understand the main concepts of the problem, you can easily solve any problem where similar concepts are applied.

Whenever a teacher uses examples in order to explain a concept, all students tend to remember those examples, but it is a mistake to do so. If you give proper time and attention to your practice with proper technique, then you will definitely be able to score a good mark in your examination if you create your own formula that you won't forget later.

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