SOLUTION: Find the sum of the first 12 terms of the arithmetic sequence given by: an=5n a. 391 b.780 c.390 d.360 Note; In the an on the problem the n is at the lower right side of the

Algebra ->  Average -> SOLUTION: Find the sum of the first 12 terms of the arithmetic sequence given by: an=5n a. 391 b.780 c.390 d.360 Note; In the an on the problem the n is at the lower right side of the      Log On


   

Question 880232: Find the sum of the first 12 terms of the arithmetic sequence given by: an=5n
a. 391
b.780
c.390
d.360
Note; In the an on the problem the n is at the lower right side of the a
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
a[1] = 5 and a[12] = 60
S[12] = (12/2)(5 + 60) = 390