I know there may be duplicates, But I have not found any question with a concrete answer for the case I am treating.
If I have a determinant:
And I want to solve it for x:
In general, there may be real negative roots, and also imaginary roots.
Question: How can I make Mathematica give me only the real and positive roots of the solution?
Attemp: I tried using
Assumptions but it seems to only work for assuming constants under derivatives. Also I tried with:
but it doesn't work either.