已知f(x)为二次函数,不等式f(x)+2<0的解集为 ( -1, 1 3 ) ,且对任意α,β∈R恒有f(sinα)≤0,f(2+cosβ)≥0.数列a n 满足a 1 =1, 3 a n+1 =1- 1 f′( a n ) (n∈N × ) (Ⅰ)求函数f(x)的解析式; (Ⅱ)设 b n = 1 a n ,求数列b n 的通项公式; (Ⅲ)若(Ⅱ)中数列b n 的前n项和为S n ,求数列S n ?cos(b n π)的前n项和T n .
【单选题】...he says he used to read me, and is rather charmingly deferential, prefac ing his remarks by ‘Of course it’s not for me to suggest to you...’ and then ...
【单选题】...he says he used to read me, and is rather charmingly deferential, prefac ing his remarks by ‘Of course it’s not for me to suggest to you...’ and then ...
【简答题】Fears of death are not so extensive as might be supposed. In a public opinion poll of 1500 s, only about 4 percent showed evidence of direct fearing their own death. 【S1】______ Those fears that d...