9.若不等式a2-2a-1≤$\frac{|x{|}^{2}+1}{|x|}$对一切非零实数x恒成立,则实数a的取值范围是( )
A. | [-3,1] | B. | [-1,3] | C. | [-1,2] | D. | [-2,1] |
2.已知数列{an}中,a1=1,前n项和为Sn,且Sn+1=$\frac{3}{2}$Sn+1.
(1)求数列{an}的通项公式;
(2)求数列{$\frac{1}{{a}_{n}}$}的前n项和Tn.
0 249829 249837 249843 249847 249853 249855 249859 249865 249867 249873 249879 249883 249885 249889 249895 249897 249903 249907 249909 249913 249915 249919 249921 249923 249924 249925 249927 249928 249929 249931 249933 249937 249939 249943 249945 249949 249955 249957 249963 249967 249969 249973 249979 249985 249987 249993 249997 249999 250005 250009 250015 250023 266669
(1)求数列{an}的通项公式;
(2)求数列{$\frac{1}{{a}_{n}}$}的前n项和Tn.