Q15. - Algebra 2

Question

Find $S_n$  for each arithmetic series described.

$a_1=7,a_n=79, n=8$

Step-by-Step Solution

Answer

$S_n$  for the arithmetic series is $S_8=344$ .

Step 1. Given Information.

Given arithmetic series is $a_1=7,a_n=79,n=8$ .

Step 2. Calculation .

The sum  $S_n$ of the first n terms of an arithmetic series is given by   

 $S_n=\frac{n}{2}(a_1+a_n)$

Here,  $a_1=7,a_n=79,n=8$

Plugging the values:

$\begin{array}{l}{S}_n=\frac{n}{2}(a_1+a_n)\\ S_8=\frac{8}{2}(7+79)\\ S_8=4\left(86\right)\\ S_8=344\end{array}$

Step 3. Conclusion .

Hence, the sum is $S_8=344$ .