## Thinking Mathematically (6th Edition)

$a_{12}=-43$
The $n^{th}$ term of an arithmetic sequence can be found using the formula: $a_n = a_1 + (n-1)d$ where d = common difference $a_1$ = first term $\\a_n= n^{th} \text{ term}$ The given arithmetic sequence has: $a_1 = 12 \\d=-5$ Use the formula above to find the 12th term: $a_n=a_1+(n-1)(d) \\a_{12}=12 + (12-1)(-5) \\a_{12}=12+11(-5) \\a_{12}=12+(-55) \\a_{12}=-43$