|Nasser M. Abbasi|
This is not a good way to use DSolve.
Assuming you are solving a differential equation by hand. Why would you put floating point numbers for the parameter themselves instead of symbol names?
When you solve a simple ODE for the pendulum for example, x''- g/L x=0. Will you put actual floating point numbers for the gravity and length in there before you solve it? Why? These are constants. Why not use the symbolic name for them?
When you obtain the solution, you can always replace the values of these constants by numerical values.
Otherwise, you'd have to solve the ODE each time when you change L or g in the above example.