diketahui deret feometri : 3+6+12+24+48+... di tanya S9

a=3
r=2
[tex]s9 = \frac{a ({r}^{9} - 1) }{r - 1} \\ s9 = \frac{3 ({2}^{9} - 1) }{2 - 1} \\ s9 = 3 \times 511 \\ s9 = 1533[/tex]