Respostas

2013-11-11T11:39:55-02:00
A1 = 3
a2 = 6
q = a2/a1
q = 6/3
q = 2
Sn = 765
n = ...
Sn = a1.(1-q^(n-1)) / 1-q
765 = 3.(1-2^(n-1) / 1-2
765/3 = (1-2^(n-1) / (-1)
(1-2^(n-1) = -255
-2^(n-1) = -255-1
-2^(n-1) = -256
2^(n-1) = 2^7
n-1 = 7
n = 7+1
n = 8
12 4 12