Misalkan U1, U2, U3, U4, U5 adalah lima suku pertama deret geometri. Jika log U1 + log U2 + log U3 + log U4 + log U5 = 5 log 3, maka U3 =..... A. 5 B. 4 C. 3 D.

Deret Geometri

log u1 + log u2 + log u3 + log u4 + log u5 = 5 log 3
log (u1.u2.u3.u4.u5) = log 3^5
u1 . u2 . u3 . u4 . u5 = 3^5
a^5 . r^(1+2+3+4) = 3^5
a^5 r^10 = 3^5
(ar^2)^5 = 3^5
ar^2 = 3

U3 = ar^2 = 3