SOLUTION: In an AP the first term is 4 and the nth term is 36. Given that the sum of the first n terms is 363, find n and the common difference of the AP.

Algebra ->  Sequences-and-series -> SOLUTION: In an AP the first term is 4 and the nth term is 36. Given that the sum of the first n terms is 363, find n and the common difference of the AP.       Log On


   

Question 888397: In an AP the first term is 4 and the nth term is 36. Given that the sum of the first n terms is
363, find n and the common difference of the AP.
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
S = ½(a + an)n
363 = ½(4 + 36)n
363 = ½(40)n
363 = 20n
363/20=n
n=18.15 which is not possible
n must be a positive integer