Question

Tolong dibantu, maaf banyak tanya

Answer 1

.
Bilangan antara 400 dan 900

• kelipatan 3
402, 405, ... , 897

n = (897 - 402)/3 + 1 = 166
Sn = n/2 (a + Un)
S166 = 166/2 (402 + 897) = 107817

• kelipatan 7
406, 413, ... , 896

n = (896 - 406)/7 + 1 = 71
S71 = 71/2 (406 + 896l) = 46221

• kelipatan 3 dan 7 (kelipatan 21)
420, 441, ... , 882

n = (882 - 420)/21 + 1 = 23
S23 = 23/2 (420 + 882) = 14973

Hasil penjumlahan yg diminta pd soal
= S166 + S71 - S23
= 107817 + 46221 - 14973
= 139065 → jawaban

#seru