[tex]3^x[/tex] is an exponential function, and as such it is always positive, but never zero, and it is upperly unbounded.
Think of this function as "9 plus something", where that "something", is always positive, never zero and can be as large as you like.
We deduce that the result of this sum is always strictly greater than 9, and it can get as big as we like.
In other words, the range of the function is [tex](9,\infty)[/tex]
