Jumlah bilangan kelipatan 9 antara 200-400 a.6376 b.6633 c.6906 d.7633

jawabannya 6.633
caranya
207,...,...,396
a = 207
b = 9
Un = 396

a+(n-1).b = 396
207 + (n-1). 9 = 396
207 + 9n -9 = 396
9n = 396+9-207
9n = 198
n = 22

Sn= n/2 (a+Un)
= 22/2 (207+396)
= 11 . 603
= 6.633

semoga membantu :)