Tentukan nilai x jika di ketahui deret berikut A) 1+3+9+....+x=364

jawab
dereet geometri
1 + 3 + 9 + ...+ x + 364
a= 1
r = 3

Sn = a(rⁿ - 1) / ( r - 1)
364 = 1(3ⁿ -1) /(2)
3ⁿ - 1 = 2(364)
3ⁿ = 728 + 1 = 729
3ⁿ= (3)⁶
n = 6

u6  = a r⁶⁻¹  = 1 .3⁵ = 243