15.若f1(x)=sinx,f2(x)=f1′(x),f3(x)=f2′(x),…fk+1(x)=fk′(x),则f2007($\frac{π}{3}$),( )
| A. | -$\frac{\sqrt{3}}{2}$ | B. | -$\frac{1}{2}$ | C. | $\frac{\sqrt{3}}{2}$ | D. | $\frac{1}{2}$ |
14.已知点A(-2,3)在抛物线y2=2px的准线上,抛物线焦点为F,则直线AF的斜率为( )
| A. | -$\frac{1}{2}$ | B. | -$\frac{3}{4}$ | C. | -1 | D. | -$\frac{4}{3}$ |
13.下列命题中的真命题是( )
| A. | 命题“垂直于同一个平面的两个平面平行”的逆否命题 | |
| B. | 若a<b,则|a|<|b| | |
| C. | 命题“若x>1,且y>1,则x+y>2”的否命题 | |
| D. | ?x∈(0,$\frac{π}{2}$),sinx<x |
12.已知命题p:?x∈R,x2-x+1<0,则¬p是( )
0 240525 240533 240539 240543 240549 240551 240555 240561 240563 240569 240575 240579 240581 240585 240591 240593 240599 240603 240605 240609 240611 240615 240617 240619 240620 240621 240623 240624 240625 240627 240629 240633 240635 240639 240641 240645 240651 240653 240659 240663 240665 240669 240675 240681 240683 240689 240693 240695 240701 240705 240711 240719 266669
| A. | ?x∈R,x2-x+1<0 | B. | ?x∈R,x2-x+1≥0 | C. | ?x∈R,x2-x+1<0 | D. | ?x∈R,x2-x+1≥0 |