18.下列函数中,在(0,+∞)上为增函数的是( )
| A. | y=-2x2-3 | B. | y=2x2-3x | C. | y=3x | D. | $y={log_{\frac{1}{2}}}x$ |
17.设P={x|x≤1},Q={x|-1≤x≤2},那么P∩Q=( )
| A. | {x|-1<x<1} | B. | {x|-1≤x<2} | C. | {x|1≤x<2} | D. | {x|-1≤x≤1} |
16.已知函数f(x)=x2+2x-3,则f(-5)=( )
| A. | -38 | B. | 12 | C. | 17 | D. | 32 |
15.下列各式中关系符号运用正确的是( )
| A. | 1⊆{0,1,2} | B. | ∅?{0,1,2} | C. | ∅⊆{2,0,1} | D. | {1}∈{0,1,2} |
13.等比数列{an}的前n项和为Sn,若Sn=3•2n+k(n∈N*,k为常数),则k值为( )
| A. | -3 | B. | 3 | C. | -1 | D. | 1 |
12.不等式x>$\frac{1}{x}$的解集为( )
| A. | (-1,0)∪(1,+∞) | B. | (-∞,-1)∪(0,1) | C. | (-∞,-1)∪(1,+∞) | D. | (-1,1) |
9.下列说法正确的是( )
0 233519 233527 233533 233537 233543 233545 233549 233555 233557 233563 233569 233573 233575 233579 233585 233587 233593 233597 233599 233603 233605 233609 233611 233613 233614 233615 233617 233618 233619 233621 233623 233627 233629 233633 233635 233639 233645 233647 233653 233657 233659 233663 233669 233675 233677 233683 233687 233689 233695 233699 233705 233713 266669
| A. | 命题“若a≥b,则a2≥b2”的逆否命题为“若a2≤b2,则a≤b” | |
| B. | “x=1”是“x2-3x+2=0”的必要不充分条件 | |
| C. | 若p∧q为假命题,则p,q均为假命题 | |
| D. | 对于命题p:?x∈R,x2+x+1>0,则¬p:?x0∈R,x02+x0+1≤0 |