Jumlah 6 suku pertama dari 18+9+4 1/2 adalah? Jawabannya yg benar yg mana ya? A. 35 7/16 B. 37 7/16 C. 38 7/16 D. 39 7/16

dik. deret geometri:
18+9+4½+.... didapat
a=18
r=9/18=½

dit S6?
Sn=a(1 - r^n)/(1 - r)
S6=18(1-(½)^6)/(1-½)
S6=18(63/64)/½
S6=36.63/64
S6=9.63/16
S6=35 7/16

[tex]sn = \frac{ {a(1 - r)}^{n} }{1 - r} \\ a = 18 \: \: \: r = \frac{1}{2} \\ sn = \frac{ {18(1 - \frac{1}{2} )}^{n} }{1 - \frac{1}{2} } \\ sn = \frac{ {3}^{2} \times 2( { \frac{1}{2}) }^{n} }{ \frac{1}{2} } \\ sn = {3}^{2} \times {2}^{2 - n} \\ s6 = {3}^{2} \times {2}^{ 2 - 6 } = \frac{ {3}^{2} }{ {2}^{4} } = \frac{9}{16} [/tex]