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

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

A=3, b=n2-n1=4

Sn= frac{1}{2} n {2a+(n-1)b}
528= frac{1}{2} n {2.3+(n-1)4}
528=3n+2n-2
528=5n-2
528+2=5n
530=5n
n= frac{530}{5}
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