Just create a function, then use fsolve from the optimization toolbox. There is no reason to use symbolic variables in that case. Often people think they need to create symbolic variables. A function handle is sufficient.
I think too often people assume they need to use symbolic variables, just because they don't know the value of a variable. For example, solve the problem:
Of course, we know the answer is x = +/- sqrt(2), and the symbolic toolbox will tell us that. So we might define x as symbolic. Then define f as x^2-2, and use solve on f.
Instead, define a function handle,
Now just call a rootfinder (fzero) or for problems with multiple variables, fsolve. You will get a numerical result, thus 1.41421..., accurate to some number of digits.
There are good examples of the use of fzero & fsolve in the documentation, so I'm not going to retype that.