حل تشریحی سوال شماره 230 ریاضی و آمار 3 انسانی

الف)

$r=\frac{1}{5},a_n=a_1{r}^{n-1}=\frac{1}{2}{\left(\frac{1}{5}\right)}^{n-1}$

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ب)

$\frac{a_{n+1}}{a_n}=\frac{1}{5},a_1=\frac{1}{2}$  یا                           $a_{n+1}=\frac{1}{5}{a}_n,a_1=\frac{1}{2}$                   

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