Answer:
262143
Step-by-step explanation:
[tex]a_{n} = a r^{n - 1}[/tex] a = 3 n = 5 [tex]a_{5} = 768[/tex]
768 = 3(r)^4 where r is the common ratio
r^4 = 256
r = 4
S = [tex]\frac{a(r^{n}-1) }{r - 1}[/tex] n = 9 r = 4 a = 3
S = [tex]\frac{3(4^{9}-1) }{4 - 1}[/tex] = [tex]\frac{3(262144-1) }{3}[/tex]
= 262143
