diketahui deret artmatika17.20.23.26 tentukan jumlah tiga puluh suku pertama deret tersebut???

a = 17
b = 3
S30 = 30/2 (2.17 + 29.3)
S30 = 15 (34 + 87)
S30 = 15 (121)
S30 = 1815

Kelas 8 Matematika
Bab Barisan dan Deret Bilangan

17, 20, 23, 26, ....

b = U2 - U1
b = 20 - 17
b = 3

Sn = n/2 . (2a + (n - 1) . b)

S30 = 30/2 . (2 . 17 + 29 . 3)
S30 = 15 . (34 + 87)
S30 = 15 . 121
S30 = 1.815