For each sequence, decide whether it could be arithmetic, geometric, or neither.
For each sequence, decide whether it could be arithmetic, geometric, or neither.
\(\begin{array}{|l|l|c|} \hline 1. & 25,5,1,\ldots & \text{geometric} \quad r=\dfrac{1}{5} \\ \hline 2. & 25,19,13,\ldots & \text{arithmetic} \quad d=-6 \\ \hline 3. & 4,9,16,\ldots \\ & 4,10,16,\ldots & \text{arithmetic} \quad d=6 \\ & 4,8,16,\ldots & \text{geometric} \quad r=2 \\ \hline 4. & 50,60,70,\ldots & \text{arithmetic} \quad d=10 \\ \hline 5. & \dfrac{1}{2},3,18,\ldots & \text{geometric} \quad r = 6 \\ \hline \end{array}\)