## Thinking Mathematically (6th Edition)

$a_n=a_1+(n-1)d$; $\text{first term}$; $\text{common difference}$
Recall: In an arithmetic sequences, the $n^{\text{th}}$ term is given by the formula: $$a_n=a_1+(n-1)d$$ where $d$=common difference $a_1$=first term Thus, the missing expressions in the given statements (in order) are: $a_n=a_1+(n-1)(d$; $\text{first term}$; $\text{common difference}$