Question

If the following sequence is an arithmetic progression, find its general term.
-5, 2, 9, 16, 23, 30, .......... is

• A. $7n-12$
• B. $6n-12$
• C. $5n-12$
• D. $4n-12$

Answer 1

The correct option is A $7n-12$

We can observe the difference between two consecutives terms is equal:
$2-(-5)=9-2=16-9=23-16=7$

Hence, the sequence is an arithmetic progression with first term $a=-5$ and common difference $d=7$.
General term of an AP is $t_n=a+(n-1)d$
$t_n=-5+(n-1)\times 7$
$t_n=7n-12$