Week 1 – My Arithmetic Sequence

13, 26, 39, 52, 65…

$t_n$ = $t_1$ + d(n – 1)

( $t_{50}$ ) = (13) + (13)[(50) – 1]

$t_{50}$ = 13 + 13 · 49

$t_{50}$ = 13 + 637

$t_{50}$ = 650

$S_n$ = $\frac{n}{2}$ ( $t_1$ + $t_n$ )

( $S_{50}$ ) = $\frac{(50)}{2}$ [(13) + (650)]

$S_{50}$ = 25 · 663

$S_{50}$ = 16575

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