已知等差数列{an}的首项为a,公差为b,且不等式log2(ax^2-3x+6)>2的解集为{xb}

ax^2-3x+6>4,a>0
x=1和x=b是ax^2-3x+6=4的两根；
求得a=1,b=2
an=2n+1,Sn=n^2
Tn=1/(1*3)+1/(3*5)+……+1/((2n+1)*(2n+3))
=0.5*(1-1/3+1/3-1/5+……+1/(2n+1)-1/(2n+3))
=0.5*(1-1/(2n+3))
=(n+1)/(2n+3)