F.1 sequence

The general term of a sequence is n/2(2n+1) .
Find (a) the first five terms of sequence,
(b)25th term of the sequence.


(a)
When n = 1: T(1) = 1/2(2 x 1 + 1) = 1/6
When n = 2: T(2) = 1/2(2 x 2 + 1) = 1/10
When n = 3: T(3) = 1/2(2 x 3 + 1) = 1/14
When n = 4: T(4) = 1/2(2 x 4 + 1) = 1/18
When n = 5: T(5) = 1/2(2 x 5 + 1) = 1/22

The first five terms are 1/6, 1/10, 1/14, 1/18, 1/22. …… (answer)


(b)
When n = 25: T(25) = 1/2(2 x 25 + 1) = 1/102 …… (answer)