You can recognize that it is easy to write an equation that has no analytical solution? In fact, you just did exactly that! Yes, it is true that some problems actually do have an analytical solution, even though it is impossible to solve for it, or even if the symbolic toolbox just gets lost.
The empty solution result tells you that MATLAB was unable to find a solution.
If you have values for all of those parameters, then substitute them so that now your problem involves only x. Then you can use vpasolve or fzero.
