Answer
Formula for $a_{n}$ term of the given sequence = $a_{1}$ + (n - 1) d.
Where
$a_{1}$ = first term
d = Common difference
n = $n^{th}$ number of term
$20^{th}$ term of sequence = 97
Work Step by Step
Given arithmetic sequence = 2, 7, 12, 17- - - - -
Common difference between consecutive term = 17 - 12 = 12 - 7 = 7 - 2 = 5.
Formula for $a_{n}$ term of the given sequence = $a_{1}$ + (n - 1) d.
Where
$a_{1}$ = first term
d = Common difference
n = $n^{th}$ number of term
$20^{th}$ term of sequence = 2 + (20 - 1) $\times$ 5
= 2 + 19$\times$5
= 2 + 95
= 97
