~~ #JawabPakaiCara ~~ Kalo ada yg kurang jelas silahkan tanya dikolom komentar.

[tex]U_5 = \frac{1}{3} \\ ar^5^-^1=\frac{1}{3} \\ ar^4 = \frac{1}{3} \\ a( \frac{1}{3} )^4 = \frac{1}{3} \\ a( \frac{1}{81})=\frac{1}{3} \\ a= \frac{81}{3} =27[/tex]

Maka suku ke-9
[tex]U_9 = ar^9^-^1 \\ U_9=27 \times ( \frac{1}{3} )^8 \\ U_9 = 3^3 \times 3^-^8 \\ U_9 = 3^-^5 \\ U_9 = \frac{1}{3^5} = \frac{1}{243} [/tex]