1.设数列{an}为等比数列,则下面四个数列:
(1){an3};
(2){pan}(p为非零常数);
(3){anan+1};
(4){an+an+1}.
其中是等比数列的有几个( )
(1){an3};
(2){pan}(p为非零常数);
(3){anan+1};
(4){an+an+1}.
其中是等比数列的有几个( )
| A. | 1 | B. | 2 | C. | 3 | D. | 4 |
20.给出下列数列:
(1)0,0,0,…;
(2)1,11,111,1111,…;
(3)1,2,3,5,8,…;
(4)-5,-3,-1,1,3,…;
(5)2,4,8,16,….
其中等差数列有( )
(1)0,0,0,…;
(2)1,11,111,1111,…;
(3)1,2,3,5,8,…;
(4)-5,-3,-1,1,3,…;
(5)2,4,8,16,….
其中等差数列有( )
| A. | 1个 | B. | 2个 | C. | 3个 | D. | 4个 |
18.已知平行四边形ABCD的两条对角线交于点M,点P是BD上任意一点,若|$\overrightarrow{AD}$|=2,|$\overrightarrow{AB}$|=1,且∠BAD=60°,则$\overrightarrow{AP}$•$\overrightarrow{CM}$的取值范围是( )
| A. | [1,$\frac{7}{4}$] | B. | [-$\frac{5}{2}$,-1] | C. | [0,$\sqrt{2}$] | D. | [-1,$\sqrt{2}$] |
17.已知函数f(x)=$\left\{\begin{array}{l}{lo{g}_{a}(2-x),x≤1}\\{|x-5|-1,3≤x≤7}\end{array}\right.$(a>0且a≠1)的图象上关于直线x=1对称的点有且仅有一对,则实数a的取值范围是( )
0 234224 234232 234238 234242 234248 234250 234254 234260 234262 234268 234274 234278 234280 234284 234290 234292 234298 234302 234304 234308 234310 234314 234316 234318 234319 234320 234322 234323 234324 234326 234328 234332 234334 234338 234340 234344 234350 234352 234358 234362 234364 234368 234374 234380 234382 234388 234392 234394 234400 234404 234410 234418 266669
| A. | [$\frac{1}{7}$,$\frac{1}{5}$]∪{3} | B. | [3,5)∪{$\frac{1}{7}$} | C. | [$\frac{1}{7}$,$\frac{1}{3}$]∪{5} | D. | [3,7)∪{$\frac{1}{5}$} |