Question

Julia owns 13 books. She buys two new books every week. Which arithmetic sequence describes the number of books she has?
A. a1 = 13; an = an − 1 + 2
B. a1 = 2; an= an − 1 + 13
C. a1 = 13; an = an + 1 + 2
D. a1 = 2; an= an +1+13

Answer 1

A. Because she starts with 13 books and each week adds 2, the recurrence is a1 = 13 and a_n = a_{n−1} + 2.