集合M={0,1,2}的子集为( )
| A、{0},{1},{2} |
| B、{0},{1},{2},{1,2} |
| C、{0},{1},{2},{1,2} |
| D、{0},{1},{2},{1,2},{0,1},{0,2},{0,1,2},∅ |
若函数y=f(x)是函数y=ax(a>0,且a≠1)的反函数,其图象经过点(2,1),则f(x)=( )
| A、log2x | ||
B、log
| ||
C、
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| D、x2 |
| A、{0},{1},{2} |
| B、{0},{1},{2},{1,2} |
| C、{0},{1},{2},{1,2} |
| D、{0},{1},{2},{1,2},{0,1},{0,2},{0,1,2},∅ |
| A、log2x | ||
B、log
| ||
C、
| ||
| D、x2 |