tolong nomor 8 ya please

Penyelesaian:

barisan bilangan: 16, 17, 18, ..., 115

jumlah total bilangan...?

Jawab

dari barisan bilangan didapat:
a = 16 
b = 1

Un = a+(n-1)b
115 = 16+n-1(1)
n = 100

Sn = n/2(2a+n-1(b))
= 100/2 (2(16) + 100 - 1)(1)
= 50 (32 + 99)
= 50(131)
= 6550