Question

If the fifth term of the expansion (a^2/3 + a^-1)ⁿ does not contain ‘a’. Then n is equal to :

A. 2 

B. 5 

C. 10 

D. None of these

Answer 1

Option : (C)

Given :

(a^2/3 + a^-1)ⁿ

⇒ 2n-8-12 = 0 

⇒ n = 10