SOLUTION: The sum of the first 5 terms of 3+7+11+...is

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Question 847803: The sum of the first 5 terms of 3+7+11+...is
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
add 4 to the last term
3,7,11,15,19
S = ½(2a + d(n-1))n
S = ½(2*3 + 4(4))5
S = ½(6 + 16)5
S = 11*5
s=55