Question

Diket. barisan 1/27 , 1/9 , 1/3 , ... hasil penjumlahan suku ke 4 dan suku ke 7 adalah...

Answer 1

R = 1/9 ÷ 1/27 = 3

Un = a × r^(n-1)

U4 + U7 = a × r^3 + a × r^6 = 1/27 ( 3^3 + 3^6 )

U4 + U7 = 1/27 ( 27 + 729 )

Answer 2

Geometri
a= 1/27
r = 1/9 ÷ 1/27 = 1/9 x27 = 3

U4 = ar^3
= 1/27 . 3^3
= 1/27 . 27
= 1

U7 = ar^6
U7 = 1/27 . 3^6
= 1/27 . 729
= 729/27
= 27

Jumlah = 1+27 = 28