Loading [MathJax]/jax/output/HTML-CSS/jax.js
Home / Aptitude Tests / Further Mathematics / The sum of the first...
The sum of the first n terms of a linear sequence is \(S_{n}...

The sum of the first n terms of a linear sequence is Sn=n2+2n. Determine the general term of the sequence.

A.

n + 1

B.

2n + 1

C.

3n + 1

D.

4n + 1

Correct answer is B

Sn=n2(2a+(n1)d=n2+2n

n(2a+(n1)d=2n2+4n

2an+n2dnd=2n2+4n

n2d=2n2

d=2

(2ad)n=4n

2ad=42a=4+d=4+2=6

a=3

Tn=a+(n1)d

= 3+(n1)2=3+2n2=2n+1