Lgx-9/x=0, the independent variable must be increased, so it must be x >；; 9 can make lgx-9/x=0, so choose d.

Or another way of thinking,

Because the function y=f(x)=lgx-

nine

x

On (0, +∞) is an increasing function,

f(9)=lg9- 1 0，f(9)？ f( 10)