【简答题】已知数列{a n }中,a 1 =2,a n -a n-1 -2n=0(n≥2,n∈N), (1)写出a 2 ,a 3 的值(只写结果)并求出数列{a n }的通项公式; (2)设 ,若对任意的n,当m∈[-1,1]时,不等式t 2 -2mt+ >b n 恒成立,求实数t的取值范围。
【简答题】已知数列{a n }中,a 1 =2,a n -a n-1 -2n=0(n≥2,n∈N). (1)写出a 2 、a 3 的值(只写结果)并求出数列{a n }的通项公式; (2)设 b n = 1 a n+1 + 1 a n+2 + 1 a n+3 +…+ 1 a 2n ,若对任意的n,当m∈[-1,1]时,不等式 t 2 -2mt+ 1 6 > b n 恒成立,求实数t的取值范围.
【简答题】数列 的首项为1,其余各项为1或2,且在第 个1和第 个1之间有 个2,即数列 为:1,2,1,2,2,2,1,2,2,2,2,2,1,…,记数列 的前 项和为 ,则 __ ; ___ .
【简答题】数列 的项是由1或2构成,且首项为1,在第 个1和第 个1之间有 个2,即数列 为:1,2,1,2,2,2,1,2,2,2,2,2,1,…,记数列 的前 项和为 ,则 ; .
【单选题】I suppose that there used to be a fairy in the woods, _______?
【单选题】Suppose that there were 25 people who had a reservation price of $500, and the 26th person had a reservation price of $200. What would the equilibrium price be if there were 24 apartments to rent?
【判断题】Suppose that there exist two parameter values satisfying that moment conditions equal 0, then it is possible to obtain a consistent consistent GMM estimator (the model is not identified).