b1+b2+b3=log(1/2)(a1)+log(1/2)(a2)+log(1/2)(a3)=log(1/2)(a1a2a3)=6 a1a2a3=1/2^6 a2a3=1/32 a1qa1q^2=1/32 q^3=1/8=(1/2)^3 q=1/2 an=a1q^(n-1)=(1/2)*(1/2)^(n-1)=1/2^n