The sum of first n terms of an A.P. is (4n2 + 2n). The nth term of the A.P. is :
(6n − 2)
(8n − 2)
(6n + 2)
(8n + 2)
1 Like
We know that,
Sn = 4n2 + 2n
Tn = Sn - Sn - 1
= 4n2 + 2n - [4(n - 1)2 + 2(n - 1)]
= 4n2 + 2n - [4(n2 - 2n + 1) + 2n - 2]
= 4n2 + 2n - [4n2 - 8n + 4 + 2n - 2]
= 4n2 + 2n -[4n2 - 6n + 2]
= 4n2 + 2n - 4n2 + 6n - 2
= 8n - 2.
Hence, option 2 is the correct option.
Answered By
The sum of first 30 odd natural numbers is:
800
900
729
1249
The 7th term of an A.P. is 4 and its common difference is −4. The first term of the A.P. is :
32
28
24
36
There are total 9 terms in an A.P. If the last term and the sum of all the terms are 28 and 144 respectively, then the first term is :
1
7
4
5