How do you write the first five terms of the geometric sequence $a_n = 5a_(n-1)$ ; $a_1 = 3$ ?

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Answer 1 · 2016-01-19T13:55:38

$3, 15, 75, 375, 1875$

$a_n = a_1r^(n - 1)$

$a_n = 5a_(n - 1)$

$a_1 = 3$

$a_2 = 3r$

But
$a_2 = 5a_(2 - 1) = 5a_1$

$=> 3r = 5a_1$
$=> 3r = 5*3$
$=> r = 5$

Using $a_n = a_1r^(n - 1)$ with $a_1 = 3$ and $r = 5$ , the first 5 terms are

$3, 15, 75, 375, 1875$

How do you write the first five terms of the geometric sequence a_n = 5a_(n-1)a_n = 5a_(n-1); a_1 = 3a_1 = 3?