tell whether the sequence is arithmetic. if it is, what is the common difference? 10, 15, 21, 28, . . .
The given sequence is not arithmetic because the differences between consecutive terms are not constant. Observing the differences:
15 - 10 = 5
21 - 15 = 6
28 - 21 = 7
The differences are not the same, which means the sequence is not arithmetic.