## Algebra and Trigonometry 10th Edition

$a_3-a_2=\frac{7}{8}-\frac{15}{16}=\frac{14}{16}-\frac{15}{16}=-\frac{1}{16}= a_2-a_1=\frac{15}{16}-1=\frac{-1}{16}$, thus this is an arithmetic sequence.