Check sibling questions

Ex 9.4.4 - Chapter 9 Class 11 Sequences and Series (Term 1)

Last updated at May 29, 2018 by

Ex 9.4. 4 - Find sum of series 1/ 1 x 2 + 1/ 2 x 3 + 1/ 3 x 4 - Finding sum from nth number

Ex 9.4.4 - Chapter 9 Class 11 Sequences and Series - Part 2
Ex 9.4.4 - Chapter 9 Class 11 Sequences and Series - Part 3

This video is only available for Teachoo black users

Subscribe Now

Transcript

Ex 9.4, 4 Find the sum to n terms of the series 1/(1 2) + 1/(2 3) + 1/(3 4) + nth term of series 1/(1 2) + 1/(2 3) + 1/(3 4) + is 1/( ( + 1)) an = 1/( ( + 1)) = (( + 1) )/( ( + 1)) = (( + 1))/( ( + 1)) /( ( + 1)) = 1/ 1/(( + 1)) Now, an = 1/ 1/(( + 1)) Adding all terms Sn = ("1 " " " 1/2) + (1/2 " " " " 1/3) + (1/3 " " " " 1/4) + +(1/( 1) " " " " 1/ )+ (1/ " " " " 1/( + 1)) Sn = 1 1/2 + 1/2 1/3 + 1/3 1/4 + + 1/( 1) " " " " 1/ + 1/ 1/( + 1) Sn = 1 1/( + 1) Sn = (( + 1) 1)/( + 1) Sn = ( + 1 1)/( + 1) Sn = ( + 0)/( + 1) Sn = /( + 1) Thus, the required sum is /( + 1)

Davneet Singh's photo - Teacher, Engineer, Marketer

Made by

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.