已知等差数列{a n }的公差d大于0,且a 2 、a 5 是方程x 2 -12x+27=0的两根,数列{b n }的前n项和为T n ,且 T n =1- 1 2 b n . (1)求数列{a n }、{b n }的通项公式; (2)设数列{a n }的前n项和为S n ,试判断n≥4时 1 b n 与S n+1 的大小,并用数学归纳法证明你的结论.
【简答题】&8226;Read the text below about the advantages of learning to keyboard quickly. &8226;In most of the lines (34-45) there is one extra word. It is either grammatically incorrect or does not fit in with...