Misc 12 - Chapter 8 Class 11 Sequences and Series

Last updated at Dec. 16, 2024 by

Slide57.JPG

Slide58.JPG
Slide59.JPG

Go Ad-free

Transcript

Misc 12 Find the 20th term of the series 2 × 4 + 4 × 6 + 6 × 8 + … + n terms. Now, an = [nth term of 2, 4, 6 …] × [nth term of 4, 6, 8 …] = (2n) (2n + 2) = (2n) (2(n + 1)) = 4n (n + 1) Thus, nth term of series 2 × 4 + 4 × 6 + 6 × 8… is an = 4n (n + 1) We need to find 20th term of given series Putting n = 20 a20 = 4 × 2(20 + 1) = 80 (21) = 1680 Hence 20th term of series is 1680

Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo