g(x)是函数f(x)=loga(x)的反函数,即g(x)=a^x
且满足f(9)=2,即loga(9)=2则a=3
g(-log9(2))=3^(-log9(2)= 3^log9(1/2)=3^(log3(1/2)-log3(9))=3^log3(1/2)/3^log3(9)=(1/2)/2=1/4