hitunglah jumlah dari bilangan di bawah ini 8+7+9+3+...+1/27+1/81

jawab


= (8+ 7) + ( 9 + 3 + ...+ 1/27 + 1/81)

p = 8 + 7  = 15
q = 9+ 3 + ...+1/81
a= 9 
r= 1/3 
un = 1/81

a. rⁿ⁻¹ = 1/81
9 .(1/3)ⁿ⁻¹ = 1/81
(3⁻)ⁿ⁻¹ = 1/ (9*81) = 1/729= 3⁻⁶
-n + 1 = -6
n = 7

q = s7 =  9.(1 - 1/3⁷)/(1- 1/3)
q = s7 = 9 (3/2) (2186/2187)
q = s7 = 13 ⁴⁰/₈₁


p + q = 15 +  13 ⁴⁰/₈₁ = 28  ⁴⁰/₈₁