## College Algebra 7th Edition

RECALL: The sum of the first $n$ terms of an arithmetic sequence can be found using the formula: $S_n=\dfrac{n}{2}\left(a + a_n\right)$ where $n$ = number of terms $a$ = first term $a_n$ = $n^{th}$ term The formula above can be rewritten as: $S_n = n\left(\dfrac{a+a_n}{2}\right)$ Notice that in the formula above, $\dfrac{a+a_n}{2}$ represents the average of $a$ and $a_n$. Thus, the given statement is true.