Question

Find the eighteenth term of the arithmetic sequence whose first term is 9 and whose common difference is - 1.

Answer 1

The eighteenth term of the arithmetic sequence with a first term of 9 and a common difference of -1 is -8.

Step-by-step explanation:

The eighteenth term of an arithmetic sequence with a first term of 9 and a common difference of -1 can be found using the formula for the nth term of an arithmetic sequence: an = a1 + (n - 1)d, where an is the nth term, a1 is the first term, n is the term number, and d is the common difference.

For the eighteenth term (n=18), this becomes: a18 = 9 + (18 - 1)(-1) = 9 - 17 = -8.