Common ratio r = - 1/4
[tex]\begin{gathered} a_n=a_1\cdot(r^{n-1}) \\ r=\frac{a_2}{a_1} \\ a_1=\frac{a_2}{r}=\frac{16}{-\frac{1}{4}} \\ a_1=-64 \end{gathered}[/tex][tex]\begin{gathered} a_9=-64_{}\cdot(-\frac{1}{4})^{9-1}=-64\cdot(-\frac{1}{4})^8 \\ a_9=-64\cdot\frac{1}{65536} \\ a_9=-\frac{1}{1024} \end{gathered}[/tex]