a1+a6=a1+a1q^5=33
a1q^2*a1q^3=a1^2q^5=32
a1+32/a1=33
a1=32或 a1=1n代入第一式,可解得q=1/2,或q=2,因为an+1a1=32,故an=32*(1/2)^(n-1)
Tn=lga1+lga2+lga3+.+lgan
=lg(a1*a2*.an)
=lg{a1^n*q^[(1+n-1)(n-1)/2]}
=lg{2^5n*2^[-n*(n-1)/2]}
=lg{2^[5n-n*(n-1)/2]}
=[5n-n*(n-1)/2]*lg2