递推藏巧思,构造等比解锁通项
题目答案解析 在数列${a_n}$中,$a_1=0$,$a_{n+1}=2a_n - 3^n - n^2 + 2n + 1$,则$a_n =$________. $2^n - 3^n + n^2$ 【题目】在数列${a_n}$中,$a_1=0$,$a_{n+1}=2a_n - 3^n - n^2 + 2n + ...
复合函数定义域陷阱迷局
已知$f(x) = 1 + \log_3 x(1 \leq x \leq 9)$,设$g(x) = f^2(x) + f(x^2)$,则函数$y = g(x)$的值域为_______. ➽答案 解析 $[2, 7]$ 由题意得$\begin{cases} 1 \leq x \leq 9 \\ 1 \leq x^2 ...




