## Algebra and Trigonometry 10th Edition

The graph labeled as (a) matches with $a_n=18(\frac{2}{3})^{n-1}$
$a_n=a_1r^{n-1}$ $a_n=18(\frac{2}{3})^{n-1}$ $a_1=18$ $r=\frac{2}{3}$ Since $a_1\gt0$ and $0\lt r\lt1$ the sequence is decreasing and all the terms are positive.