(1)设数列{an}的公比为q,由a1=2,a3-a2=12,
得2q2-2q-12=0,即q2-q-6=0.
解得q=3或q=-2,
∵q>0,∴q=-2不合题意舍去,
∴an=2×3n?1;
(2)由bn=log3(
)+log3an,且an=2×3n?1,得3n 2
bn=log3(
×2×3n?1)=log332n?1=2n?1,3n 2
∴数列{bn}是首项b1=1,公差d=2的等差数列,
∴Sn=(a1+a2+…+an)+(b1+b2+…+bn)=
+2(3n?1) 3?1
=3n-1+n2.n(1+2n?1) 2