Question

Jumlah bilangan kelipatan 3 antara 400 dan 500 adalah......

Answer 1

Materi Baris dan Deret
Kelas IX

a = 402
Un = 498
b = 3

Un = a+(n-1)b
498 = 402 + 3n - 3
3n = 99
n = 33

Sn = n/2 (a+Un)
S33 = 33/2 (402+498)
S33 = 14.850

Answer 2

Bilangan itu adalah : 402, 405, 408, ....., 498
a = 402, b = 3

Un = a + (n - 1)b
498 = 402 + (n - 1)3
498 = 402 + 3n - 3
498 = 399 + 3n
3n = 498 - 399
3n = 99
n= 33

Sn = 1/2 n (a + Un)
= 1/2 x 33 x (402 + 498)
= 16,5 x 900
Sn = 14.850