Sarah's Blog

Week 1 – Arithmetic Sequence

Arithmetic sequence: 12, 15, 18, 21, 24

Determine $t_{50}$

$t_{n}=$ $t_{1}+ (n-1)d$

$t_{50}=12+{(50-1)}3$

$t_{50}=12+{(49)}3$

$t_{50}=12+147$

$t_{50}=159$

General equation for $t_{n}$

$t_{n}=$ $t_{1}+ (n-1)d$

$t_{n}=12+{(n-1)}3$

$t_{n}=12+3n+3$

$t_{n}=15+3n$

Determine $S_{50}$

$S_n=\frac{n}{2}(2t_1 + (n -1)d)$

$S_{50}=\frac{50}{2}(24+(49)3)$

$S_{50}=25(24+147)$

$S_{50}=25(171)$

$S_{50}=4275$

Leave a Reply Cancel reply