3.已知集合A={x|y=log2x,y<0},$B=\left\{{y\left|{y={{(\frac{1}{2})}^x},0<x<1}\right.}\right\}$,则A∪B=( )
A. | (0,1) | B. | $(\frac{1}{2},+∞)$ | C. | $(\frac{1}{2},1)$ | D. | (-∞,1) |
2.下列函数中,为奇函数的是( )
A. | y=2x+$\frac{1}{2^x}$ | B. | y=x,x∈(0,1] | C. | y=x3+x | D. | y=x3+1 |
1.已知全集U={1,2,3,4,5,6},集合A={1,3,5,6},则∁UA等于( )
A. | {1,3,5} | B. | {2,4,6} | C. | {2,4} | D. | {1,3,5,6} |
20.设D为△ABC所在平面内一点,$\overrightarrow{AD}=2\overrightarrow{CD}$,则( )
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A. | $\overrightarrow{BD}=-\overrightarrow{BA}+2\overrightarrow{BC}$ | B. | $\overrightarrow{BD}=2\overrightarrow{BA}-\overrightarrow{BC}$ | C. | $\overrightarrow{BD}=\overrightarrow{BA}+2\overrightarrow{BC}$ | D. | $\overrightarrow{BD}=\frac{1}{3}\overrightarrow{BA}+\frac{2}{3}\overrightarrow{BC}$ |