Explicit solution could not be found.

I am looking for the value of a parameter,a, when an eigenvalue equals 0. I found the Jacobian matix and have the correct equation for when the eigenvalue is 0.When I try solving for 'a' I get the error: explicit solution could not be found. I know the correct value for a is somewhere between 7.393 and 7.394 through other means. I would like to know the exact value thought.

[Walter Roberson]

What if the exact value is an irrational number such as 2*sqrt(3) ? That would take an infinite number of digits to represent.

If the solution to your matrices involve a polynomial of degree 5 or higher, it might not be possible to find an analytic form for the solution.