17.已知圆C:(x-a)2+(y-a)2=2a2(a>0)及其外一点A(0,2).若圆C上存在点T满足∠CAT=$\frac{π}{4}$,则实数a的取值范围是( )
| A. | (-∞,1) | B. | $[\sqrt{3}-1,1)$ | C. | $[\sqrt{3}-1,1]$ | D. | $[\sqrt{3}-1,+∞)$ |
16.若函数f(x)=ax3-x2+x-5在(-∞,+∞)上单调递增,则a的取值范围是( )
| A. | a>$\frac{1}{3}$ | B. | a<$\frac{1}{3}$ | C. | a≤$\frac{1}{3}$ | D. | a≥$\frac{1}{3}$ |
15.设集合M={-1,1},N={x|x2-4<0},则下列结论正确的是( )
| A. | N⊆M | B. | N∩M=∅ | C. | M⊆N | D. | M∪N=R |
12.若点M是△ABC所在平面内的一点,且满足5$\overrightarrow{AM}$=$\overrightarrow{AB}$+3$\overrightarrow{AC}$,则△MBC与△ABC的面积比为( )
0 233501 233509 233515 233519 233525 233527 233531 233537 233539 233545 233551 233555 233557 233561 233567 233569 233575 233579 233581 233585 233587 233591 233593 233595 233596 233597 233599 233600 233601 233603 233605 233609 233611 233615 233617 233621 233627 233629 233635 233639 233641 233645 233651 233657 233659 233665 233669 233671 233677 233681 233687 233695 266669
| A. | $\frac{1}{5}$ | B. | $\frac{2}{5}$ | C. | $\frac{3}{5}$ | D. | $\frac{4}{5}$ |