题目

设函数f(x)=logax(a＞0,a≠1)满足f(9)=2,则f-1（log92）等于（    ）A.                  B.2                 C.-2                     D.- 答案：解析：∵f(9)=2,∴loga9=2.∴a=3,f-1(x)=ax.∴f-1(log92)=.f-1(log92)=.故选A.答案:A

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