9.半径为1的圆O内切于正方形ABCD,正六边形EFGHPR内接于圆O,当EFGHPR绕圆心O旋转时,$\overrightarrow{AE}$•$\overrightarrow{OF}$的取值范围是( )
| A. | [1-$\sqrt{2}$,1+$\sqrt{2}$] | B. | [-1$-\sqrt{2}$,-1+$\sqrt{2}$] | C. | [$\frac{1}{2}$-$\sqrt{2}$,$\frac{1}{2}$$+\sqrt{2}$] | D. | [$-\frac{1}{2}$-$\sqrt{2}$,$-\frac{1}{2}$+$\sqrt{2}$] |
6.对于任意实数a,b,定义max{a,b}=$\left\{\begin{array}{l}{a}&{a≥b}\\{b}&{a<b}\end{array}\right.$,已知在[-4,4]上的奇函数f(x)满足:当0<x≤4时,f(x)=max{2x-1,2-x},若方程f(x)-mx2+1=0恰有两个根,则m的取值范围是( )
| A. | [-$\frac{7}{8}$,0)∪($\frac{{e}^{2}1{n}^{2}2}{4}$,1] | B. | [-$\frac{7}{8}$,0)∪($\frac{1}{e}$,1] | ||
| C. | (-1,-$\frac{7}{8}$)∪($\frac{{e}^{2}1{n}^{2}2}{4}$,2] | D. | (-1,0)∪($\frac{1}{e}$,1] |
4.已知方程$\frac{{x}^{2}}{k-1}$-$\frac{{y}^{2}}{|k|}$=-1表示双曲线,则实数k的取值范围为( )
0 252870 252878 252884 252888 252894 252896 252900 252906 252908 252914 252920 252924 252926 252930 252936 252938 252944 252948 252950 252954 252956 252960 252962 252964 252965 252966 252968 252969 252970 252972 252974 252978 252980 252984 252986 252990 252996 252998 253004 253008 253010 253014 253020 253026 253028 253034 253038 253040 253046 253050 253056 253064 266669
| A. | (-∞,0)∪(0,1)∪(1,+∞) | B. | (1,+∞) | C. | (0,1) | D. | (-∞,0) |