My Arithmetic Sequence – Jerrico's Blog

Sequence:

$4,9,14,19,24$ …

Formulas:

$t_n = t_1 + (n-1)d$

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

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

Skill check:

a = 4 d = 5

general equation:

$t_n = 4 + (n-1) 5$

$t_n = 4 + 5n - 5$

$t_n = 9 + 5n - 5$

$t_{50}$

$t_{50} = 4 + (49) 5$

$t_{50} = 4 + 245$

$t_{50} = 249$

a = 4 d = 5 $t_n = 249$

$S_{50} = \frac{50}{2} (4 + 249)$

$S_{50} = 25 (253)$

$S_{50} = 6325$