## anonymous one year ago What is the sum of the first 28 terms of this arithmetic sequence? 69, 75, 81, 87, 93, 99, … A. 2,436 B. 4,200 C. 4,320 D. 4,368

1. chrisdbest

B

2. chrisdbest

I actually wrote them all down, sorry.

3. freckles

$S_n=\frac{n(a_1+a_n)}{2}$ Sn is the sum of the first n terms a1 is the first term an is the nth term

4. freckles

you can find the 28 term by using: $a_n=a_1+d(n-1) \\ a_{28}=69+d(28-1)$ I will let you say what d is

5. anonymous

THANKS