## College Algebra (6th Edition)

If -83 is last term of $a_{n}$ then there are 22 terms in $a_{n}$. = 22 terms
From graph First term $a_{1}$ = 1 Second term $a_{2}$ = -3 Third term $a_{3}$ = -7 Sequence = 1, -3, -7, . . . . . Common difference (d) = -7 + 3 = -3 - 1 = -4 Given last term ($a_{l}$)= -83 Number of terms = $\frac{Last term - first term }{d}$ + 1 = $\frac{a_{l} - a_{1}}{d}$ + 1 = $\frac{-83 - 1}{-4}$ + 1 = $\frac{-84}{-4}$ + 1 = 21 + 1 = 22 If -83 is last term of $a_{n}$ then there are 22 terms in $a_{n}$.