解①∵ bn=T1,n=1;bn=Tn-T(n-1),n ≥2;且4Tn-12Sn=13n, an=-(2n+3)/2,∴ n=1时,b1=T1=3S1+13/4=3a1+13=-15/2+13=-17/4,n≥2时,bn=Tn-Tn-1=13n/4+3Sn-13(n-1)/4-3Sn-1
=13/4+3(Sn-Sn-1)=13/4+3an
=13/4-3(2n+3)/2=-3n-5/4当n=1时,-3n-5/4=-17/4=b1∴ bn=-3n-5/4(n∈N)解②: ∵A={x|x= 2an,n∈N}={x|x=-3-2n, n∈N}B={x|x=4bn, n∈N}={x|x= |