diketahui barisan bilangan 3,7,11,15 jika Sn = 528 maka n =

a=3, b=n2-n1=4

Sn=[tex] \frac{1}{2} [/tex] n {2a+(n-1)b}
528=[tex] \frac{1}{2} [/tex] n {2.3+(n-1)4}
528=3n+2n-2
528=5n-2
528+2=5n
530=5n
n=[tex] \frac{530}{5} [/tex]
n=106

Sn = 1/2n  [2(a) + (n-1)b]
528= 1/2 n [2(3) + (n-1)4]
528= n/2 (6 + 4n - 4)
528= n/2 (2 + 4n)
528= n + 2n^2
2n^2 + n - 528 = 0