15.已知函数f(x)=-x2+bln(x+1)在[0,+∞)上单调递减,则b的取值范围( )
| A. | [0,+∞) | B. | [-$\frac{1}{2}$,+∞) | C. | (-∞,0] | D. | (-∞,-$\frac{1}{2}$] |
13.数列{an}为等比数列,则下列结论中不正确的是( )
| A. | $\{{a_n}^2\}$是等比数列 | B. | {an•an+1}是等比数列 | ||
| C. | $\{\frac{1}{a_n}\}$是等比数列 | D. | {lgan}是等差数列 |
10.若函数f(x)是偶函数,其定义域为(-∞,+∞),且在[0,+∞)上是减函数,则不等式f(lgx)>f(-1)成立的 x的取值范围为( )
| A. | $(\frac{1}{10},10)$ | B. | $(0,\frac{1}{10})$ | C. | (0,10) | D. | (10,+∞) |
9.已知平面α的一个法向量$\overrightarrow n$=(2,1,2),点A(-2,3,0)在α内,则P(1,1,4)到α的距离为( )
0 233529 233537 233543 233547 233553 233555 233559 233565 233567 233573 233579 233583 233585 233589 233595 233597 233603 233607 233609 233613 233615 233619 233621 233623 233624 233625 233627 233628 233629 233631 233633 233637 233639 233643 233645 233649 233655 233657 233663 233667 233669 233673 233679 233685 233687 233693 233697 233699 233705 233709 233715 233723 266669
| A. | 10 | B. | 4 | C. | $\frac{8}{3}$ | D. | $\frac{10}{3}$ |