Question

Given the arithmetic sequence an = −1 + 7(n − 1), what is the domain for n?

Answer 1

An arithmetic sequence is that in which the consecutive terms share or have the same difference commonly referred to as the "common difference". The terms in the arithmetic sequence always starts with the term 0 or the initial value. In this item, the value of n should be greater than or equal to. Therefore the answer is the second choice. 

If we are to get the first term of the arithmetic sequence, it will become,
                     first term:
           a0 = (-1) + 7(0 - 1) = -8

Therefore, the first term is equal to -8.