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Find $4+12+36+\ldots$ up to 6 terms

Option: 1

1525


Option: 2

1456


Option: 3

1320


Option: 4

1120


Answers (1)

best_answer

$a=4, \quad r=12 / 4=3, \quad n=6$

Here $r>1$. Hence,

$\mathrm{S}_6=\mathrm{a}\left(\mathrm{r}^{\mathrm{n}}-1\right) \mathrm{r}-1=4\left(3^6-1\right) 3-1=4(729-1) / 2=4 \times 728 / 2=2 \times 728=1456$

Posted by

Deependra Verma

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