设函数f(x)=的反函数f-1(x)，且f-1()=a，则f(a+7)=( )A．-2

设函数f(x)=的反函数f^-1(x)，且f^-1()=a，则f(a+7)=( )

A．-2 B．-1 C．1 D．2

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答案：

A 【解析】本题考查分段函数及反函数知识；据题意由f^-1()=a即f(a)=，由分段函数解析式知只能2^a-4=a=1，故f(a+7)=f(8)=-log₃9=-2.

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设函数f(x)=的反函数f-1(x)，且f-1()=a，则f(a+7)=( )A．-2

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