## RD Sharma Solutions for Class 11 Maths Chapter 21 - Free PDF Download

## FAQs on RD Sharma Class 11 Maths Solutions Chapter 21 - Some Special Series

**1. What is the formula for the sum of the square of first N natural numbers?**

Natural numbers represent the set of all whole numbers except 0. The calculation of the sum of the square of the first n natural number is easy if you know the formula for its calculation. The formula is universal and can be applied for any value of n. Therefore, each student must remember this formula so that they are able to solve questions easily. The sum of the square of the first N natural number can be calculated using the following formula:

( n(n+1)(2n+1) /6)

**2. What is an AGP series?**

The Arithmetic-Geometric Progression (AGP) is a sequence of which each term can be expressed as the product of an arithmetic progression and a geometric progression. The arithmetic-geometric series, commonly known as AGP, are formed by multiplying the corresponding terms of an arithmetic progression and geometric progression. The general form of an AGP is:

a, (a+d)r, (a+2d)r^{2}, (a+3d)r^{3}, (a+4d)r^{4}, ……….. (a+(n-1)d)r^{n-1
}

Here, ‘a’ is the first term, ‘d’ is a common difference and ‘r’ is the common ratio.

**3. How can we determine the nth term of an arithmetic sequence?**

Arithmetic sequences are easy to determine. If you are provided with the common difference and first term in the question, you can simply put the values in the formula and determine the required term. Given an arithmetic sequence with the first term a1 and the common difference d, then the nth (or general) term is determined by an=a_{1}+(n-1)d. Students should practice questions related to this concept as these types of questions often appear in exams and are highly scoring.

**4. How will I benefit from RD Sharma Solutions for Class 11 Math Chapter 21?**

RD Sharma Solutions for Class 11 Chapter 21, that is, some special series provided by Vedantu are very helpful for the students. These solutions will help students in preparing better for the exams. The step by step explanation provided by the team of experts at Vedantu will solve all the possible doubts that may arise in a student's mind. Moreover, all the formulae related to the chapter are also mentioned along with the solutions which will help students revise the formulae every now and then.

**5. Can I get access to RD Sharma Solutions for Class 11 Math Chapter 21 while I am offline?**

RD Sharma Solutions for Class 11 Math Chapter 21 are available in the form of a PDF file on the official website of Vedantu. The students can download the PDF file from the official website absolutely free of cost after registering through their mail id. Once the students have downloaded the PDF file on their system, they can view the solutions whenever and wherever they want without the requirement of any internet connection. This ensures that there is no hurdle between a student and his education.