# Ex 8.2,5 - Chapter 8 Class 11 Binomial Theorem

Last updated at May 29, 2018 by Teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Ex 8.2,5 Find the 4th term in the expansion of (x 2y)12 . We know that General term of expansion (a + b)n is Tr+1 = nCr an r br We need to find fourth term i.e. T4 = T3+1 of expansion (x 12y)12 Putting r = 3 , a = x , b = 2y , n = 12 T3+1 = 12C3 (x)12 3 ( 2y)3 = 12 ! 3! (12 3) ! x9 ( 2)3 (y)3 = 12! 3! 9! x9 ( 8) y3 = 12 11 10 9! 3 2 9 ! ( 8) x9 y3 = 12 11 10 ( 8) 6 x9 y3 = 2 11 10 ( 8) x9 y3 = 220 8 x9 y3 = 1760 x9 y3

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.