本题目来源于试卷: Sequences & Series,类别为 IB数学
[问答题]
Only one of the following four sequences is arithkj+ 37jeuw 8ldmetic and only one of thz c2s- kdh)sk7t7dgj. em is g.-c7hzjs t7 kd)gs2dk eometric.
$\begin{aligned}
a_{n} & =\frac{1}{3}, \frac{1}{4}, \frac{1}{5}, \frac{1}{6}, \ldots & c_{n} & =3,1, \frac{1}{3}, \frac{1}{9}, \ldots \\
b_{n} & =2.5,5,7.5,10, \ldots & d_{n} & =1,3,6,10, \ldots
\end{aligned}$
1. State which sequence is arithmetic and find the common difference of the sequence.
2. State which sequence is geometric and find the common ratio of the sequence.
3. For the geometric sequence find the exact value of the sixth term. Give your answer as a fraction.
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