Question

Find the expression for the given sequence
3, 6, 9, 12 .......(take n as 'n'th term)
and find the 7th term in the sequence.

• A. 3n, 21
• B. 3n - 1, 20
• C. 3n + 1, 22
• D. 3n + 2, 23

Answer 1

The correct option is A 3n, 21

In the given sequence of numbers,

1st number = $3\times 1$ = 3
2nd number = $3\times 2$ = 6
3rd number = $3\times 3$ = 9
4th number = $3\times 4$ = 12
. .
. .
. .
. .
. .
nth number = $3\times n$
= 3n

$\therefore$ The expression for the sequence is 3n.

now, the 7th term = $3\times 7$ = 21.

Hence, the 7th term is 21.