13.已知f(x)=sinx+cosx+sin2x,若?t∈R,x∈R,asint+3a+1≥f(x)恒成立,则实数a的取值范围是( )
| A. | [0,+∞) | B. | $[\frac{{\sqrt{2}}}{2},+∞)$ | C. | $[{\frac{{\sqrt{2}}}{4},+∞})$ | D. | $[\sqrt{2},+∞)$ |
8.已知命题p:若x>y,则x2>y2;命题q:“a=0”是“f(x)=$\frac{1}{x}$+a为奇函数”的充分必要条件.在命题①p∧q;②p∨q;③p∧¬q;④¬p∨q中,真命题是( )
| A. | ①③ | B. | ①④ | C. | ②③ | D. | ②④ |
7.若$f(x)=({m-1}){x^{{m^2}-4m+3}}$是幂函数,则( )
| A. | f(x)在定义域上单调递减 | B. | f(x)在定义域上单调递增 | ||
| C. | f(x)是奇函数 | D. | f(x)是偶函数 |
5.若复数z满足z(1-i)=1+i,则|z|=( )
| A. | 1 | B. | $\sqrt{2}$ | C. | i | D. | -i |
4.集合A={x|x2-x>0},B={x|log2x>1},则A∩B=( )
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| A. | (0,1) | B. | (1,2) | C. | (2,+∞) | D. | (0,1)∪(2,+∞) |