# Week 1 – My Arithmetic Sequence

5, 20, 35, 50, 65

To find the 50th term, use the formula: $t_n$ = $t_1$ + (n – 1) d.

20 – 15 = 5

35 – 15 = 20

D= +15

$t_{50}$ = 5 + (50 -1) ⋅ 15.

$t_{50}$ = 5 + (49) ⋅ 15

$t_{50}$ = 5 + 735

$t_{50}$ = 740

Find $S_{50}$ with the formula $S_n$$\frac{n}{2}$ ( $t_1$ + $t_n$ )

$t_{50}$ =$\frac{50}{2}$ ( 5 + 740)

$t_{50}$ = 25 (745)

$t_{50}$ = 18,625