6.已知复数Z=$\frac{1-\sqrt{3}i}{\sqrt{3}+i}$,$\overline{Z}$是Z的共轭复数,则Z•$\overline{Z}$=( )
A. | $\frac{1}{2}$ | B. | $\frac{1}{4}$ | C. | 4 | D. | 1 |
4.已知函数f(x)=2lnx+1在点(1,f(1))处的切线为l,点(an,an+1)在l上,且a1=2,则a2015=( )
A. | 22014-1 | B. | 22014+1 | C. | 22015-1 | D. | 22015+1 |
2.已知复数Z=$\frac{1-\sqrt{3}i}{(\sqrt{3}+i)^{2}}$,$\overline{Z}$是Z的共轭复数,则Z•$\overline{Z}$=( )
A. | $\frac{1}{2}$ | B. | $\frac{1}{4}$ | C. | 2 | D. | 4 |
1.已知集合M={x|(1-x)x>0},N={y|y=x2+2x+3},则(∁RM)∩N=( )
A. | {x|0<x<1} | B. | {x|x>1} | C. | {x|x≥2} | D. | {x|1<x<2} |
19.(理)在直三棱柱ABC-A1B1C1中,AC=3,BC=4,AB=5,AA1=4,则异面直线AC1与B1C所成角的余弦值为( )
0 250693 250701 250707 250711 250717 250719 250723 250729 250731 250737 250743 250747 250749 250753 250759 250761 250767 250771 250773 250777 250779 250783 250785 250787 250788 250789 250791 250792 250793 250795 250797 250801 250803 250807 250809 250813 250819 250821 250827 250831 250833 250837 250843 250849 250851 250857 250861 250863 250869 250873 250879 250887 266669
A. | $\frac{{\sqrt{5}}}{5}$ | B. | $\frac{{2\sqrt{5}}}{5}$ | C. | $\frac{{2\sqrt{2}}}{5}$ | D. | $-\frac{{2\sqrt{2}}}{5}$ |