Question

What is the third term of (a+b)^11

Answer 1

(r+1)th term = nCr a^(n-r) b^r

Answer 2

here r = 2, n = 11

3rd term = 11C2 a^9 b^2

- can you continue from here?

Answer 3

11C2 a^9 b^2 is the answer?

Answer 4

well we need to calculate 11C2 - which is the number of combinations of 2 in 11

= 11* 10
----- = 55
2 * 1

sao 3rd term is 55a^9 b^2

Answer 5

Thank you for your help

Answer 6

yw