Week 1 – Arithmetic Sequence

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

My arithmetic Sequence: 5, 10, 15, 20, 25

$t_1=5$ $t_{50}=?$ $S_{50}=?$

d = 5

$t_{50}=5+(50-1)5$ $t_{50}=250$

$S_{50}=\frac{50}{2}(5+50)$ $S_{50}=25(55)$

$S_{50}= 1375$ $t_{50}=250$

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