Question

Which term of ap 3,15,27 will be more than its 21st term

Answer 1

Answer:

22nd term is more than its 21st term

Answer 2

Answer:

Solution:

Common difference of series = (n+1) – n

We get 15 – 3, 27 – 15……  

Common difference = 12

First term of series = 3.  

Therefore, the 21st term of the series is  

Required term after adding 120 = 120 + 243 = 363.

Let

First value of the series is a = 3

Common difference = 12  

term is 363.  

Value of n is :- Tn = 3+12(n-1) which is 363= 3+12(n-1) then n=31