4.等比数列{an}中,若a3=7,S3=21,则公比q的值为( )
| A. | $\frac{1}{2}或3$ | B. | $-\frac{1}{2}或3$ | C. | $\frac{1}{2}或1$ | D. | $-\frac{1}{2}或1$ |
3.若实数x,y,满足3x-4y-5=0,则$\sqrt{{x^2}+{y^2}}$的最小值是( )
| A. | $\sqrt{5}$ | B. | 5 | C. | $\frac{\sqrt{5}}{5}$ | D. | 1 |
2.若命题“?x0∈R,x02+(a-1)x0+1≤0”的否定是真命题,则实数a的取值范围是( )
| A. | [-1,3] | B. | (-1,3) | C. | (-∞,-1]∪[3,+∞) | D. | (-∞,-1)∪(3,+∞) |
1.已知全集U={-3,-2,-1,0,1,2,3},集合A={x|-2≤x≤3},B={0,1,2},则A∩(∁UB)=( )
| A. | {0,1,2} | B. | {-2,-1,3} | C. | {-3} | D. | {-2,-1,0,1,2,3} |
20.已知f(x)=$\sqrt{3}$sinxcosx-sin2x,把y=f(x)的图象向右平移$\frac{π}{12}$个单位,再向上平移$\frac{1}{2}$个单位,得到y=g(x)的图象,则g($\frac{π}{4}$)=( )
| A. | $\frac{\sqrt{2}}{2}$ | B. | 1 | C. | -$\frac{\sqrt{2}}{2}$ | D. | -1 |
17.对于任意向量$\overrightarrow{a},\overrightarrow{b}$,下列命题中正确的是( )
| A. | 若$\overrightarrow{a},\overrightarrow{b}$满足|$\overrightarrow{a}$|>|$\overrightarrow{b}$|,且$\overrightarrow{a}$与$\overrightarrow{b}$同向,则$\overrightarrow{a}$>$\overrightarrow{b}$ | B. | |$\overrightarrow{a}$+$\overrightarrow{b}$|≤|$\overrightarrow{a}$|+|$\overrightarrow{b}$| | ||
| C. | |$\overrightarrow{a}$•$\overrightarrow{b}$|=|$\overrightarrow{a}$|•|$\overrightarrow{b}$| | D. | |$\overrightarrow{a}$-$\overrightarrow{b}$|≤|$\overrightarrow{a}$|-|$\overrightarrow{b}$| |
16.若将函数y=2sin2x的图象向左平移$\frac{π}{12}$个单位长度,则平移后图象的对称轴为( )
0 240336 240344 240350 240354 240360 240362 240366 240372 240374 240380 240386 240390 240392 240396 240402 240404 240410 240414 240416 240420 240422 240426 240428 240430 240431 240432 240434 240435 240436 240438 240440 240444 240446 240450 240452 240456 240462 240464 240470 240474 240476 240480 240486 240492 240494 240500 240504 240506 240512 240516 240522 240530 266669
| A. | $x=kπ+\frac{π}{6}(k∈Z)$ | B. | x=$\frac{kπ}{2}$+$\frac{π}{6}$(k∈Z) | C. | $x=kπ+\frac{5π}{24}(k∈Z)$ | D. | $x=\frac{kπ}{2}+\frac{5π}{24}(k∈Z)$ |