Question

How do you know if it is an arithmetic sequence?

Answer 1

Arithmetic Sequence: It is a sequence where each term increases by adding or subtracting some constant.

For example, $a,b,c,...$ is a sequence

if $b-c=c-b$ then it is an arithmetic sequence

Hence, if the difference of $2$ consecutive numbers in the sequence is always the same or constant then the sequence can be considered as an arithmetic sequence.