Answer
General Formula: $a_n=6+(n-1)(3)$
$a_{20} = 63$
Work Step by Step
The formula for the general term (the nth term) of an arithmetic sequence is:
$a_n=a_1+(n−1)d$
where
d = common difference
$a_1$ = first term
$a_n$ = nth term
n = term number
The given arithmetic sequence has:
$a_1=6$ and $d=3$
Substitute these into the given formula above:
$a_n = 6 + (n-1)(3)$
Thus,
$a_{20} = 6+(20-1)(3)
\\a_{20}=6+19(3)
\\a_{20}=6+57
\\a_{20}=63$
