Subscribe to our Youtube Channel - https://you.tube/teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Ex 9.4, 9 Find the sum to n terms of the series whose nth terms is given by n2 + 2n Given an = n2 + 2n Now, sum of n terms is Now, = 2 + 4 + 8 + + 2n This is GP with first term A = 2 & common ratio R = 4/2 = 2 We know that sum of n term in GP Sn = ( (R^n 1))/(R 1) Putting values Now from (1) Putting values = (n(n+1)(2n+1))/6 + 2(2n 1) Thus, the required sum is (n(n+1)(2n+1))/6 + 2(2n 1)

Ex 9.4

Ex 9.4, 1
Not in Syllabus - CBSE Exams 2021

Ex 9.4, 2 Not in Syllabus - CBSE Exams 2021

Ex 9.4, 3 Not in Syllabus - CBSE Exams 2021

Ex 9.4.4 Important Not in Syllabus - CBSE Exams 2021

Ex 9.4, 5 Not in Syllabus - CBSE Exams 2021

Ex 9.4, 6 Not in Syllabus - CBSE Exams 2021

Ex 9.4, 7 Important Not in Syllabus - CBSE Exams 2021

Ex 9.4, 8 Not in Syllabus - CBSE Exams 2021

Ex 9.4, 9 Important Not in Syllabus - CBSE Exams 2021 You are here

Ex 9.4, 10 Important Not in Syllabus - CBSE Exams 2021

Chapter 9 Class 11 Sequences and Series

Serial order wise

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.