Sequences and Series (p-1) — Maths (commerce) STD 11 Commerce / Arts — Question
Maharashtra BoardEnglish MediumSTD 11 Commerce / ArtsMaths (commerce)Sequences and Series (p-1)1 Mark
Question
Verify whether the following sequences are G.P. If so, write tn. : $2,6,18,54, \ldots \ldots$
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Answer
$2,6,18,54, \ldots \ldots$. $\mathrm{t}_1=2, \mathrm{t}_2=6, \mathrm{t}_3=18, \mathrm{t}_4=54, \ldots$. Here, $\frac{t_2}{t_1}=\frac{t_3}{t_2}=\frac{t_4}{t_3}=3$ Since, the ratio of any two consecutive terms is a constant, the given sequence is a geometric progression. Here, $a=2, r=3$ $ \begin{aligned} & \mathrm{t}_{\mathrm{n}}=\mathrm{ar} \mathrm{r}^{\mathrm{n}-1} \\ & \therefore \mathrm{t}_{\mathrm{n}}=2\left(3^{\mathrm{n}-1}\right) \end{aligned} $
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