Question

First term of A.P. is 2,nth term =29,Sn=465,find n=?

Answer 1

Answer

N = 30

Solution

Given

First term a = 2

Nth term = 29

Sn = 465

Nth term =

An = a + ( n - 1 ) d = 29

=> 2 + ( n - 1 ) d = 29

=> ( n - 1 ) d = 27 ..... ( 1 )

Sn = n / 2 ( 2a + ( n - 1 ) d = 465

=> n / 2 ( 2(2) + 27 ) = 465

=> n / 2 ( 31 ) = 465

=> 31n = 930

=> n = 30 = ANSWER