4.已知向量$\overrightarrow{a}$=(1,0),$\overrightarrow{b}$=(0,-2),则与向量$\overrightarrow{b}$-$\overrightarrow{a}$垂直的单位向量为( )
A. | (-2,1)或(2,-1) | B. | (-1,2)或(1,-2) | ||
C. | (-$\frac{\sqrt{5}}{5}$,$\frac{2\sqrt{5}}{5}$)或($\frac{\sqrt{5}}{5}$,-$\frac{2\sqrt{5}}{5}$) | D. | (-$\frac{2\sqrt{5}}{5}$,$\frac{\sqrt{5}}{5}$)或($\frac{2\sqrt{5}}{5}$,-$\frac{\sqrt{5}}{5}$) |
3.下列函数中,在(0,+∞)上为增函数的是( )
A. | y=$\sqrt{x+1}$ | B. | y=(x-2)2 | C. | y=3-x | D. | y=log0.1(x+1) |
2.已知命题p:“?x>0,ex≥1”,则¬p为( )
A. | ?x≤0,使得ex≤1 | B. | ?x≤0,使得ex<1 | C. | ?x>0,使得ex<1 | D. | ?x>0,使得ex≤1 |
17.已知ξ~N(3,σ2),若P(ξ≤2)=0.2,则P(ξ≤4)等于( )
A. | 0.2 | B. | P(-2≤ξ≤2)=0.4 | C. | P(ξ>2)=0.2 | D. | P(ξ≤4)=0.8 |
16.计算:$\int_1^2{{{(x-1)}^5}dx}$=( )
A. | $-\frac{1}{5}$ | B. | $\frac{1}{5}$ | C. | $-\frac{1}{6}$ | D. | $\frac{1}{6}$ |
15.i是虚数单位,则$\frac{2i}{1+i}$-1=( )
0 250398 250406 250412 250416 250422 250424 250428 250434 250436 250442 250448 250452 250454 250458 250464 250466 250472 250476 250478 250482 250484 250488 250490 250492 250493 250494 250496 250497 250498 250500 250502 250506 250508 250512 250514 250518 250524 250526 250532 250536 250538 250542 250548 250554 250556 250562 250566 250568 250574 250578 250584 250592 266669
A. | 1 | B. | -1 | C. | i | D. | -i |