16.下列函数中,在区间(0,+∞)上为增函数的是( )
| A. | $f(x)=\frac{2}{x}$ | B. | f(x)=-x+1 | C. | f(x)=|x-1| | D. | f(x)=2x2+3x+1 |
15.已知函数f(x)=$\left\{\begin{array}{l}x+2,x≥2\\{x^2},0≤x<2\end{array}$,则f(f(${\frac{3}{2}}$))=( )
| A. | $\frac{9}{4}$ | B. | $\frac{7}{2}$ | C. | $\frac{17}{4}$ | D. | $\frac{81}{16}$ |
14.下列四组式子中,f(x)与g(x)表示同一函数的是( )
| A. | f(x)=x-1,x∈R,g(x)=x-1,x∈N | B. | $f(x)=\frac{{{x^2}-4}}{x+2}$,g(x)=x-2 | ||
| C. | f(x)=x,$g(x)={({\sqrt{x}})^2}$ | D. | f(x)=2x-1,g(t)=2t-1 |
13.已知集合P={1,2,3},则集合P的真子集个数为( )个.
| A. | 5 | B. | 6 | C. | 7 | D. | 8 |
9.倾斜角为θ的直线过离心率是$\frac{{\sqrt{3}}}{2}$的椭圆C:$\frac{x^2}{a^2}$+$\frac{y^2}{b^2}$=1(a>b>0)右焦点F,直线与C交于A,B两点,若$\overrightarrow{AF}$=7$\overrightarrow{FB}$,则θ=( )
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| A. | $\frac{π}{6}$ | B. | $\frac{π}{4}$ | C. | $\frac{π}{3}$ | D. | $\frac{π}{2}$ |