Tentukan nilai k jika 3+5+7....k=960

a  = 3
b = 2
un = 3 +2n - 2 = 2n+1
Sn = n/2(a+un)
960 = n/2(3 + 2n+1)
960 = n/2(2n+4)
960 = 2n^2/2 + 4n/2
960 = n^2 + 2n
n^2+2n-960 = 0
(n+32)(n-30) = 0
n = 30, n = -32(tidak memenuhi)
*k berada pada suku ke-30
u30 = 2(30)+1 = 61