Respostas

2014-01-12T18:23:18-02:00
Razão (q) = 1/2
 a_{n} =  a_{1} *  q^{n-1}  \\  \\  a_{12} =  8 *  1/2^{12-1} \\\\ a_{12} =  8 *  1/2^{11}  \\  \\  a_{12} =  8 *  1/2048 \\\\   a_{12} =  8/2048 = 1/256

Espero ter ajudado!