Week 1 – My Arithmetic Sequence

February 4, 2018February 4, 2018 by victorias2015

Sequence: 21, 27, 33, 39, 45…

$t_{50}=?$
$t_n=t_1+(n-1)d$
$t_{50}=t_1+(n-1)d$
$t_{50}=21+(50-1)6$
$t_{50}=21+(49)(6)$
$t_{50}=21+294$
$t_{50}=315$

$General Equation for t_n$
$t_n=t_1+(n-1)d$
$t_n=21+(n-1)6$
$t_n=21+6n-6$
$t_n=6n+15$

$S_{50}=?$
$S_n=\frac{n}{2}(t_1+t_n)$
$S_{50}=\frac{50}{2}(21+315)$
$S_{50}=25(21+315)$
$S_{50}=(25)(336)$
$S_{50}=8 400$

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