hasil dari 7+11+15+19+...+111=

Lihat lampiran saya, smoga membantu

bisa pakai deret aritmatika
a = 7
b = 11 - 7 = 4
Sn?

Un = a + (n-1) b
111 = 7 +(n-1) 4
111 = 7 + 4n - 4
111 - 3 = 4n
108 = 4n
n = 27

Sn = n/2(2 .a + (n-1) b)
S27 = 27/2 (2.7 +(27-1) 4)
S27 = 27/2 (14 + (26) 4)
S27 = 27/2 (14+ 104)
S27 = 27/2 (118)
S27 = 27 . 59
S27 = 1593