f[loga(x)]=a(x-1/x)/(a^2-1)令loga(x)=t，x=a^tf(t)=a(a^t-1/a^t)/(a^2-1)f(x)=a(a^x-1/a^x)/(a^2-1)
f（loga X）=（a/a^2-1)(x-1/x) 设logax=t,x=a^t ∴f(t)=a/(a²-1)*(a^t-1/a^t)
不会
