16.已知集合A={x|0≤x≤2},B={y|y=2x,x>0},则A∩B=( )
A. | (1,2] | B. | [0,1)∪(2,+∞) | C. | [0,1] | D. | [0,2] |
15.下列函数中,在区间(0,+∞)上为增函数的是( )
A. | f(x)=-$\sqrt{x+1}$ | B. | f(x)=${(\frac{1}{2})}^{x}$ | C. | f(x)=lnx+2 | D. | f(x)=x+$\frac{1}{x}$ |
12.△ABC中,点D在BC上,AD平分∠BAC,若$\overrightarrow{AB}=\overrightarrow{a}$,$\overrightarrow{AC}=\overrightarrow{b}$,|$\overrightarrow{a}$|=2,|$\overrightarrow{b}$|=3,则$\overrightarrow{AD}$=( )
A. | $\frac{2}{5}\overrightarrow{a}+\frac{3}{5}\overrightarrow{b}$ | B. | $\frac{4}{5}\overrightarrow{a}+\frac{3}{5}\overrightarrow{b}$ | C. | $\frac{3}{5}\overrightarrow{a}+\frac{4}{5}\overrightarrow{b}$ | D. | $\frac{3}{5}\overrightarrow{a}+\frac{2}{5}\overrightarrow{b}$ |
10.设a>0,b>0若$\sqrt{{3}^{5}}$是3a与3b的等比中项,则$\frac{1}{a}+\frac{1}{b}$的最小值为( )
0 252177 252185 252191 252195 252201 252203 252207 252213 252215 252221 252227 252231 252233 252237 252243 252245 252251 252255 252257 252261 252263 252267 252269 252271 252272 252273 252275 252276 252277 252279 252281 252285 252287 252291 252293 252297 252303 252305 252311 252315 252317 252321 252327 252333 252335 252341 252345 252347 252353 252357 252363 252371 266669
A. | $\frac{8}{3}$ | B. | $\frac{4}{5}$ | C. | 4 | D. | $\frac{1}{4}$ |