## College Algebra (6th Edition)

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 = - 89
Given arithmetic sequence = 6, 1, -4, -9- - - - - Common difference between consecutive term d = (-9) - (-4) = (-4)- 1 = 1 - 6 = (-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 = 6 + (20 - 1) $\times$ (-5) = 6 + 19$\times$(-5) = 6 - 95 = - 89