First create the necessary symbolic objects. Solve x-50 MATLAB will execute the above statement and return the following result. This is not due to a limitation of solve.
S solve eqnvar solves the equation eqn for the variable var.
For degree 5 or higher solve will typically return a data structure the stands in for the roots. To solve this equation in MATLAB you need to code the equations code a mass matrix and set the initial conditions and interval of integration before calling the solver ode23t. If you do not specify var the symvar function determines the variable to solve for. There are some polynomials of degree 5 or higher that solve is able to provide exact solutions for but most of them it cannot handle.