Chapter 9 - Sequences and Series - 9-2 Arithmetic Sequences - Practice and Problem-Solving Exercises - Page 575: 8

Not arithemetic

You are given the sequence $1,1,2,3,5,8$. Find the common difference (difference between consecutive terms) and if there is one, the sequence is arithmetic. Note that: $1-1=0\\ 2-1=1\\ 3-2=1\\ 5-3=2\\ 8-5=3$ \ The differences are not constant so the sequence is not arithmetic.