Question

Hitunglah jumlah bilangan kelipatan 3 antara 1 dan 300.

mohon bantuannya y ...

Answer 1

3,6,9,12,...,297
a = 3
b = 3

Un = a + (n - 1)b
297 = 3 + (n - 1) × 3
297 = 3 + 3n - 3
297 = 3n
n = 297/3
n = 99

Sn = 1/2(n)[2a + (n - 1)b]
S99 = 1/2(99)[2(3) + (99 - 1) × 3]
S99 = 49,5[6 + 98 × 3]
S99 = 49,5[6 + 294]
S99 = 49,5(300)
S99 = 14850

Jadi jumlah bilangan kelipatan 3 antara 1 dan 300 adalah 14850