## Algebra 2 Common Core

The $17^{\text{th}}$ term is $18$.
The$16^{\text{th}}$ is $21$ and the common difference is $-3$ so we simply add $-3$ to $21$ to get the $17^{\text{th}}$ term: $a_{17}=a_{16}+d$ $a_{17}=21+(-3)$ $a_{17}=18$