6.直线y=-2x+3与直线y=kx-5互相垂直,则实数k的值为( )
| A. | $\frac{1}{2}$ | B. | 2 | C. | -2 | D. | -1 |
5.已知集合A={x|-1<x<2},B={x|x≥-1},则A∩B=( )
| A. | (-1,1] | B. | (-1,2) | C. | ∅ | D. | [-1,2] |
4.数列{an}满足:a1=1,且对任意的n∈N*都有:an+1=an+n+1,则$\frac{1}{{a}_{1}}$+$\frac{1}{{a}_{2}}$+$\frac{1}{{a}_{3}}$+…+$\frac{1}{{a}_{2016}}$=( )
| A. | $\frac{2015}{2016}$ | B. | $\frac{2015}{1008}$ | C. | $\frac{2016}{2017}$ | D. | $\frac{4032}{2017}$ |
2.直线x+y+a=0半圆与y=$\sqrt{1-{x^2}}$有两个不同的交点,则a的取值范围是( )
| A. | [1,$\sqrt{2}$) | B. | [1,$\sqrt{2}$] | C. | [-$\sqrt{2}$,1] | D. | (-$\sqrt{2}$,-1] |
1.已知直线l:x+y+2=0与圆C:(x-1)2+(y+1)2=2,则圆心C到直线l的距离( )
| A. | $2\sqrt{2}$ | B. | 2 | C. | $\sqrt{2}$ | D. | $\frac{{\sqrt{2}}}{2}$ |
18.若i为虚数单位,则$\frac{{1-\sqrt{2}i}}{{\sqrt{2}+i}}$=( )
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| A. | 1+i | B. | 1-i | C. | i | D. | -i |