f(x/3)=(2x+3)/x (x≠0)
令x/3=t ,x=3t
则(2x+3)/x=(6t+3)/3t=(2t+1)/t
f(t)=(2t+1)/t
即f(x)=(2x+1)/x
y=(2x+1)/x
xy=2x+1
x=1/(y-2)
所以反函数y=1/(x-2) (x≠2)