15.不等式2≥$\frac{1}{x-1}$的解集为( )
| A. | (-$\frac{3}{2}$,1) | B. | (-∞,1)∪($\frac{3}{2}$,+∞) | C. | (1,$\frac{3}{2}$) | D. | (-∞,1)∪[$\frac{3}{2}$,+∞) |
14.已知全集U={1,2,3,4,5,6,7,8},A={2,4,6},B={1,3,5,7},则A∩(∁UB)等于( )
| A. | {2,4,6} | B. | {1,3,5} | C. | {2,4,5} | D. | {2,5} |
11.lg$\frac{1}{4}$-lg25=( )
| A. | -2 | B. | 0 | C. | 1 | D. | 2 |
10.已知函数f(x)=$\left\{\begin{array}{l}{2x+a,x≤1}\\{lo{g}_{2}x,x>1}\end{array}\right.$,若f(f($\frac{1}{2}$))=4,则a=( )
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| A. | 16 | B. | 15 | C. | 2 | D. | $\frac{2}{3}$ |